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path: root/drivers/tty/vt
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2020-06-24vt: remove superfluous parens in invert_screen and build_attrJiri Slaby
There were too many parentheses in invert_screen, remove them and align the code in invert_screen a bit. No functional change intended. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-27-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use newly defined CUR_* macrosJiri Slaby
We defined macros for all the magic constants in the previous patch. So let us use the macro in the code now. No functional change intended. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Thomas Winischhofer <thomas@winischhofer.net> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Helge Deller <deller@gmx.de> Cc: linux-usb@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Cc: linux-parisc@vger.kernel.org Acked-by: Helge Deller <deller@gmx.de> Link: https://lore.kernel.org/r/20200615074910.19267-26-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: redefine world of cursor macrosJiri Slaby
The cursor code used to use magic constants, ANDs, ORs, and some macros. Redefine all this to make some sense. In particular: * Drop CUR_DEFAULT, which is CUR_UNDERLINE. CUR_DEFAULT was used only for cur_default variable initialization, so use CUR_UNDERLINE there to make obvious what's the default. * Drop CUR_HWMASK. Instead, define CUR_SIZE() which explains it more. And use it all over the places. * Define few more masks and bits which will be used in next patches instead of magic constants. * Define CUR_MAKE to build up cursor value. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: dri-devel@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Link: https://lore.kernel.org/r/20200615074910.19267-25-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: whitespace and paren cleanup in add_softcursorJiri Slaby
Format add_softcursor according to CodingStyle. Until now, it was a mess of letters. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-24-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: synchronize types and use min in csi_XJiri Slaby
All the types are unsinged ints -- even the vpar passed to the function. So unify them and use min() to compute count instead of explicit comparison. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-23-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: make tc write more obvious in vc_con_write_normalJiri Slaby
Nested ternary operators spread over 4 lines are really evil for reading. Turn the outer one to proper 'if'. Now, we see, there is a common path, so the code can be simplified. This way, the code is understandable now. Checked using symbolic execution (klee), that the old and new behaviors are the same. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-22-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: simplify vc_attr handling in vc_con_write_normalJiri Slaby
Invert the attribute on the only place, without the need of checking 'inverse'. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-21-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: simplify condition in vc_con_write_normalJiri Slaby
Convert (!(A && !B) || C) into (!A || B || C) to improve readability. No functional changes, as was just proven by objdump. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-20-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: move normal char processing from do_con_writeJiri Slaby
vc_con_write_normal now handles the complex normal characters processing. It is no longer a part of do_con_write. So this patch makes do_con_write pretty clean and obvious. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-19-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: extract detecting control characters from do_con_writeJiri Slaby
Move the control characters detection to a separate function dubbed vc_is_control. It makes the 14 subexpressions a "bit" more readable. And also simplifies next patches. It moves also CTRL_ACTION and CTRL_ALWAYS to this new function, as they are used exclusively here. While at it, these are converted to static const variables. And we use "& BIT()" instead of ">>" and "& 1". Checked using symbolic execution (klee), that the old and new behaviors are the same. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-18-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: introduce struct vc_draw_regionJiri Slaby
For passing of draw area among functions. This makes next patches simpler. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-17-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: move translation out of do_con_writeJiri Slaby
Now that we reordered the code and the label, we can eliminate the translation into a separate function. We call it vc_translate here. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-16-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: move rescan_last_byte label earlierJiri Slaby
This removes duplicated initialization of variables (after reordering 'c' initialization). It will also allow for eliminating whole translation into a separate function in the next patch. Note that vc_state, vc_utf etc. are checked with every rescan now. But they are immutable for non-control characters where rescan might be only necessary. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-15-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: extract attribute inversion to vc_invert_attrJiri Slaby
We continue cleaning up do_con_write. This (hopefully) makes the inversion code obvious. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-14-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: rearrange vc_translate_unicodeJiri Slaby
The code was too overcomplicated. Extract vc_sanitize_unicode to a separate function and flatten the code. I believe the code is straightforward now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: separate unicode handling into vc_translate_unicodeJiri Slaby
do_con_write is complicated enough. Extract unicode handling to a separate function. For do_con_write, 249 LOCs lowered to 183 lines. Use diff -w -b to see the difference is neligible -- mostly whitespace and use of 'return's instead of 'continue's. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-12-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use modern types in do_con_writeJiri Slaby
Use bools for rescan and inverse. And true/false accordingly. Use u8 for width instead of uint8_t. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-11-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: move vc_translate to vt.c and rename itJiri Slaby
vc_translate is used only in vt.c, so move the definition from a header there. Also, it used to be a macro, so be modern and make a static inline from it. This makes the code actually readable. And as a preparation for next patches, rename it to vc_translate_ascii. vc_translate will be a wrapper for both unicode and this one. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-10-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: get rid of VT10.ID macrosJiri Slaby
VT100ID is unused, but defined twice. Kill it. VT102ID is used only in respond_ID. Define there a variable with proper type and use that instead. Then drop both defines of VT102ID too. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-9-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use tty_insert_flip_string in respond_stringJiri Slaby
Pass the length of a string to respond_string and use tty_insert_flip_string instead of a loop with tty_insert_flip_char. This simplifies the processing on the tty side. The added strlens are optimized during constant folding and propagation and the result are proper constants in assembly. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-8-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: convert vc_tab_stop to bitmapJiri Slaby
vc_tab_stop is used as a bitmap, but defined as an unsigned int array. Switch it to bitmap and convert all users to the bitmap interface. Note the difference in behavior! We no longer mask the top 24 bits away from x, hence we do not wrap tabs at 256th column. Instead, we silently drop attempts to set a tab behind 256 columns. And we will also seek by '\t' to the rightmost column, when behind that boundary. I do not think the original behavior was desired and that someone relies on that. If this turns out to be the case, we can change the added 'if's back to masks here and there instead... (Or we can increase the limit as fb consoles now have 240 chars here. And they could have more with higher than my resolution, of course.) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-6-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: switch G0/1_charset to an arrayJiri Slaby
Declare Gx_charset[2] instead of G0_charset and G1_charset. It makes the code simpler (without ternary operators). Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: deduplicate setGx codeJiri Slaby
The code for setting G0 and G1 is duplicated -- for each of them. Move the code to a separate function (vc_setGx) and distinguish the two cases by a parameter. Change if-else-if to switch which allows for slightly better optimization (decision tree). Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: switch state to boolJiri Slaby
The code currently uses bitfields to store true-false values. Switch all of that to bools. Apart from the cleanup, it saves 20B of code as many shifts, ANDs, and ORs became simple movzb's. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: introduce enum vc_intensity for intensityJiri Slaby
Introduce names (en enum) for 0, 1, and 2 constants. We now have VCI_HALF_BRIGHT, VCI_NORMAL, and VCI_BOLD instead. Apart from the cleanup, 1) the enum allows for better type checking, and 2) this saves some code. No more fiddling with bits is needed in assembly now. (OTOH, the structure is larger.) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: separate stateJiri Slaby
There are two copies of some members of struct vc_data. This is because we need to save them and restore later. Move these memebers to a separate structure called vc_state. So now instead of members like: vc_x, vc_y and vc_saved_x, vc_saved_y we have state and saved_state (of type: struct vc_state) containing state.x, state.y and saved_state.x, saved_state.y This change: * makes clear what is saved & restored * eases save & restore by using memcpy (see save_cur and restore_cur) Finally, we document the newly added struct vc_state using kernel-doc. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-09mmap locking API: convert mmap_sem commentsMichel Lespinasse
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-27vt: keyboard: avoid signed integer overflow in k_asciiDmitry Torokhov
When k_ascii is invoked several times in a row there is a potential for signed integer overflow: UBSAN: Undefined behaviour in drivers/tty/vt/keyboard.c:888:19 signed integer overflow: 10 * 1111111111 cannot be represented in type 'int' CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.11 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xce/0x128 lib/dump_stack.c:118 ubsan_epilogue+0xe/0x30 lib/ubsan.c:154 handle_overflow+0xdc/0xf0 lib/ubsan.c:184 __ubsan_handle_mul_overflow+0x2a/0x40 lib/ubsan.c:205 k_ascii+0xbf/0xd0 drivers/tty/vt/keyboard.c:888 kbd_keycode drivers/tty/vt/keyboard.c:1477 [inline] kbd_event+0x888/0x3be0 drivers/tty/vt/keyboard.c:1495 While it can be worked around by using check_mul_overflow()/ check_add_overflow(), it is better to introduce a separate flag to signal that number pad is being used to compose a symbol, and change type of the accumulator from signed to unsigned, thus avoiding undefined behavior when it overflows. Reported-by: Kyungtae Kim <kt0755@gmail.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20200525232740.GA262061@dtor-ws Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-11Merge 5.7-rc5 into tty-nextGreg Kroah-Hartman
We need the tty fixes in here too. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-04vt: fix unicode console freeing with a common interfaceNicolas Pitre
By directly using kfree() in different places we risk missing one if it is switched to using vfree(), especially if the corresponding vmalloc() is hidden away within a common abstraction. Oh wait, that's exactly what happened here. So let's fix this by creating a common abstraction for the free case as well. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Reported-by: syzbot+0bfda3ade1ee9288a1be@syzkaller.appspotmail.com Fixes: 9a98e7a80f95 ("vt: don't use kmalloc() for the unicode screen buffer") Cc: <stable@vger.kernel.org> Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2005021043110.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-27Merge 5.7-rc3 into tty-nextGreg Kroah-Hartman
We need the tty/serial fixes in here too. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-23vt: don't hardcode the mem allocation upper boundNicolas Pitre
The code in vc_do_resize() bounds the memory allocation size to avoid exceeding MAX_ORDER down the kzalloc() call chain and generating a runtime warning triggerable from user space. However, not only is it unwise to use a literal value here, but MAX_ORDER may also be configurable based on CONFIG_FORCE_MAX_ZONEORDER. Let's use KMALLOC_MAX_SIZE instead. Note that prior commit bb1107f7c605 ("mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value could not be relied upon. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Cc: <stable@vger.kernel.org> # v4.10+ Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-23vt: don't use kmalloc() for the unicode screen bufferNicolas Pitre
Even if the actual screen size is bounded in vc_do_resize(), the unicode buffer is still a little more than twice the size of the glyph buffer and may exceed MAX_ORDER down the kmalloc() path. This can be triggered from user space. Since there is no point having a physically contiguous buffer here, let's avoid the above issue as well as reducing pressure on high order allocations by using vmalloc() instead. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Cc: <stable@vger.kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org> Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003282214210.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-16vt: extract selection chars storing from vc_do_selectionJiri Slaby
Let's put it to a separate function, named vc_selection_store_chars. Again, this makes vc_do_selection a bit shorter and more readable. Having 4 local variables instead of 12 (5.6-rc1) looks much better now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200415093608.10348-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-16vt: selection, split __set_selection_kernelJiri Slaby
Handle these actions: * poking console * TIOCL_SELCLEAR * TIOCL_SELMOUSEREPORT * start/end precomputation * clear_selection if the console changed in a separate function, thus making __set_selection_kernel way shorter and more readable. The function still needs dissection, but we are approaching. This includes introduction of vc_selection and renaming __set_selection_kernel to vc_do_selection. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200415093608.10348-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-27vt: vt_ioctl: fix use-after-free in vt_in_use()Eric Biggers
vt_in_use() dereferences console_driver->ttys[i] without proper locking. This is broken because the tty can be closed and freed concurrently. We could fix this by using 'READ_ONCE(console_driver->ttys[i]) != NULL' and skipping the check of tty_struct::count. But, looking at console_driver->ttys[i] isn't really appropriate anyway because even if it is NULL the tty can still be in the process of being closed. Instead, fix it by making vt_in_use() require console_lock() and check whether the vt is allocated and has port refcount > 1. This works since following the patch "vt: vt_ioctl: fix VT_DISALLOCATE freeing in-use virtual console" the port refcount is incremented while the vt is open. Reproducer (very unreliable, but it worked for me after a few minutes): #include <fcntl.h> #include <linux/vt.h> int main() { int fd, nproc; struct vt_stat state; char ttyname[16]; fd = open("/dev/tty10", O_RDONLY); for (nproc = 1; nproc < 8; nproc *= 2) fork(); for (;;) { sprintf(ttyname, "/dev/tty%d", rand() % 8); close(open(ttyname, O_RDONLY)); ioctl(fd, VT_GETSTATE, &state); } } KASAN report: BUG: KASAN: use-after-free in vt_in_use drivers/tty/vt/vt_ioctl.c:48 [inline] BUG: KASAN: use-after-free in vt_ioctl+0x1ad3/0x1d70 drivers/tty/vt/vt_ioctl.c:657 Read of size 4 at addr ffff888065722468 by task syz-vt2/132 CPU: 0 PID: 132 Comm: syz-vt2 Not tainted 5.6.0-rc5-00130-g089b6d3654916 #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20191223_100556-anatol 04/01/2014 Call Trace: [...] vt_in_use drivers/tty/vt/vt_ioctl.c:48 [inline] vt_ioctl+0x1ad3/0x1d70 drivers/tty/vt/vt_ioctl.c:657 tty_ioctl+0x9db/0x11b0 drivers/tty/tty_io.c:2660 [...] Allocated by task 136: [...] kzalloc include/linux/slab.h:669 [inline] alloc_tty_struct+0x96/0x8a0 drivers/tty/tty_io.c:2982 tty_init_dev+0x23/0x350 drivers/tty/tty_io.c:1334 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline] tty_open+0x3ca/0xb30 drivers/tty/tty_io.c:2035 [...] Freed by task 41: [...] kfree+0xbf/0x200 mm/slab.c:3757 free_tty_struct+0x8d/0xb0 drivers/tty/tty_io.c:177 release_one_tty+0x22d/0x2f0 drivers/tty/tty_io.c:1468 process_one_work+0x7f1/0x14b0 kernel/workqueue.c:2264 worker_thread+0x8b/0xc80 kernel/workqueue.c:2410 [...] Fixes: 4001d7b7fc27 ("vt: push down the tty lock so we can see what is left to tackle") Cc: <stable@vger.kernel.org> # v3.4+ Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200322034305.210082-3-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-27vt: vt_ioctl: fix VT_DISALLOCATE freeing in-use virtual consoleEric Biggers
The VT_DISALLOCATE ioctl can free a virtual console while tty_release() is still running, causing a use-after-free in con_shutdown(). This occurs because VT_DISALLOCATE considers a virtual console's 'struct vc_data' to be unused as soon as the corresponding tty's refcount hits 0. But actually it may be still being closed. Fix this by making vc_data be reference-counted via the embedded 'struct tty_port'. A newly allocated virtual console has refcount 1. Opening it for the first time increments the refcount to 2. Closing it for the last time decrements the refcount (in tty_operations::cleanup() so that it happens late enough), as does VT_DISALLOCATE. Reproducer: #include <fcntl.h> #include <linux/vt.h> #include <sys/ioctl.h> #include <unistd.h> int main() { if (fork()) { for (;;) close(open("/dev/tty5", O_RDWR)); } else { int fd = open("/dev/tty10", O_RDWR); for (;;) ioctl(fd, VT_DISALLOCATE, 5); } } KASAN report: BUG: KASAN: use-after-free in con_shutdown+0x76/0x80 drivers/tty/vt/vt.c:3278 Write of size 8 at addr ffff88806a4ec108 by task syz_vt/129 CPU: 0 PID: 129 Comm: syz_vt Not tainted 5.6.0-rc2 #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20191223_100556-anatol 04/01/2014 Call Trace: [...] con_shutdown+0x76/0x80 drivers/tty/vt/vt.c:3278 release_tty+0xa8/0x410 drivers/tty/tty_io.c:1514 tty_release_struct+0x34/0x50 drivers/tty/tty_io.c:1629 tty_release+0x984/0xed0 drivers/tty/tty_io.c:1789 [...] Allocated by task 129: [...] kzalloc include/linux/slab.h:669 [inline] vc_allocate drivers/tty/vt/vt.c:1085 [inline] vc_allocate+0x1ac/0x680 drivers/tty/vt/vt.c:1066 con_install+0x4d/0x3f0 drivers/tty/vt/vt.c:3229 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline] tty_init_dev+0x94/0x350 drivers/tty/tty_io.c:1341 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline] tty_open+0x3ca/0xb30 drivers/tty/tty_io.c:2035 [...] Freed by task 130: [...] kfree+0xbf/0x1e0 mm/slab.c:3757 vt_disallocate drivers/tty/vt/vt_ioctl.c:300 [inline] vt_ioctl+0x16dc/0x1e30 drivers/tty/vt/vt_ioctl.c:818 tty_ioctl+0x9db/0x11b0 drivers/tty/tty_io.c:2660 [...] Fixes: 4001d7b7fc27 ("vt: push down the tty lock so we can see what is left to tackle") Cc: <stable@vger.kernel.org> # v3.4+ Reported-by: syzbot+522643ab5729b0421998@syzkaller.appspotmail.com Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200322034305.210082-2-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: indent switch-case in setterm_command properlyJiri Slaby
Shift cases one level left. This makes the code more readable and some lines need not wrap anymore. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200316065911.11024-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: selection, use rounddown() for start/endline computationJiri Slaby
We have a helper called rounddown for these modulo computations. So use it. No functional change intended and "objdump -d" proves that. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200316065911.11024-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: use min() to limit intervalsJiri Slaby
Instead of awkward ternary operator with comparison, use simple min() for blankinterval and vesa_off_interval. No functional change intended and "objdump -d" proves that. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200316065911.11024-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: selection, fix double lock introduced by a mergeJiri Slaby
The merge commit cb05c6c82fb0 (Merge 5.6-rc5 into tty-next) introduced a double lock to set_selection_kernel. vc_sel.lock is locked both in set_selection_kernel and its callee __set_selection_kernel now. Remove the latter. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: https://lore.kernel.org/r/20200316064544.4799-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-12vt: vt_ioctl: remove unnecessary console allocation checksEric Biggers
The vc_cons_allocated() checks in vt_ioctl() and vt_compat_ioctl() are unnecessary because they can only be reached by calling ioctl() on an open tty, which implies the corresponding virtual console is allocated. And even if the virtual console *could* be freed concurrently, then these checks would be broken since they aren't done under console_lock, and the vc_data is dereferenced before them anyway. So, remove these unneeded checks to avoid confusion. Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200224080326.295046-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-12vt: drop redundant might_sleep() in do_con_write()Eric Biggers
The might_sleep() in do_con_write() is redundant because console_lock() already contains might_sleep(). Remove it. Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200224073450.292892-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-10Merge 5.6-rc5 into tty-nextGreg Kroah-Hartman
We need the vt fixes in here and it resolves a merge issue with drivers/tty/vt/selection.c Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: selection, indent switch-case properlyJiri Slaby
Shift the cases one level left as this is how we are supposed to write the switch-case code according to the CodingStyle. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-9-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: selection, remove redeclaration of poke_blanked_consoleJiri Slaby
It is declared in vt_kern.h, so no need to declare it in selection.c which includes the header. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-8-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: switch vt_dont_switch to boolJiri Slaby
vt_dont_switch is pure boolean, no need for whole char. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-6-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: selection, create struct from console selection globalsJiri Slaby
Move all the selection global variables to a structure vc_selection, instantiated as vc_sel. This helps to group all the variables together and see what should be protected by the embedded lock too. It might be used later also for per-console selection support. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: selection, localize use_unicodeJiri Slaby
use_unicode needs not be global. It is used only in set_selection_kernel and sel_pos (a callee). It is also always set there prior calling sel_pos. So make use_unicode local and rename it to plain shorter "unicode". Finally, propagate it to sel_pos via parameter. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-06vt: selection, remove 2 local variables from set_selection_kernelJiri Slaby
multiplier and mode are not actually needed: * multiplier is used only in kmalloc_array, so use "use_unicode ? 4 : 1" directly * mode is used only to assign a bool in this manner: if (cond) x = true; else x = false; So do "x = cond" directly. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>