diff options
| author | Mazin Al Haddad <mazinalhaddad05@gmail.com> | 2023-12-12 11:17:21 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-20 15:44:41 +0100 |
| commit | 5a82cf64f8ad63caf6bf115642ce44ddbc64311e (patch) | |
| tree | 0ad5d2965071f91a6526f1ac8745802fc0d308e7 | |
| parent | a11ea2c08f517798e0af9ebd2b7318bf7be9f609 (diff) | |
tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf()
commit f16c6d2e58a4c2b972efcf9eb12390ee0ba3befb upstream
A null pointer dereference can happen when attempting to access the
"gsm->receive()" function in gsmld_receive_buf(). Currently, the code
assumes that gsm->receive is only called after MUX activation.
Since the gsmld_receive_buf() function can be accessed without the need to
initialize the MUX, the gsm->receive() function will not be set and a
NULL pointer dereference will occur.
Fix this by avoiding the call to "gsm->receive()" in case the function is
not initialized by adding a sanity check.
Call Trace:
<TASK>
gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861
tiocsti drivers/tty/tty_io.c:2293 [inline]
tty_ioctl+0xa75/0x15d0 drivers/tty/tty_io.c:2692
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Link: https://syzkaller.appspot.com/bug?id=bdf035c61447f8c6e0e6920315d577cb5cc35ac5
Fixes: 01aecd917114 ("tty: n_gsm: fix tty registration before control channel open")
Reported-and-tested-by: syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com
Signed-off-by: Mazin Al Haddad <mazinalhaddad05@gmail.com>
Link: https://lore.kernel.org/r/20220814015211.84180-1-mazinalhaddad05@gmail.com
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/n_gsm.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 2455f952e0aa..fa49529682ce 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2588,7 +2588,8 @@ static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp, flags = *fp++; switch (flags) { case TTY_NORMAL: - gsm->receive(gsm, *cp); + if (gsm->receive) + gsm->receive(gsm, *cp); break; case TTY_OVERRUN: case TTY_BREAK: |