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| author | Carlos O'Donell <carlos@systemhalted.org> | 2018-01-24 20:35:22 -0800 |
|---|---|---|
| committer | Carlos O'Donell <carlos@systemhalted.org> | 2018-01-25 23:43:46 -0800 |
| commit | 2ec0e7eade0ea1258acd5c6f5e5e9bfaeb5041a8 (patch) | |
| tree | 9d069618e0132fa31ab0c39eda4c95f14d50a1b0 /sysdeps/x86_64 | |
| parent | 47c4b4b060db0290022dcc37cab7b5ff4bdb5c32 (diff) | |
Revert Intel CET changes to __jmp_buf_tag (Bug 22743)
In commit cba595c350e52194e10c0006732e1991e3d0803b and commit
f81ddabffd76ac9dd600b02adbf3e1dac4bb10ec, ABI compatibility with
applications was broken by increasing the size of the on-stack
allocated __pthread_unwind_buf_t beyond the oringal size.
Applications only have the origianl space available for
__pthread_unwind_register, and __pthread_unwind_next to use,
any increase in the size of __pthread_unwind_buf_t causes these
functions to write beyond the original structure into other
on-stack variables leading to segmentation faults in common
applications like vlc. The only workaround is to version those
functions which operate on the old sized objects, but this must
happen in glibc 2.28.
Thank you to Andrew Senkevich, H.J. Lu, and Aurelien Jarno, for
submitting reports and tracking the issue down.
The commit reverts the above mentioned commits and testing on
x86_64 shows that the ABI compatibility is restored. A tst-cleanup1
regression test linked with an older glibc now passes when run
with the newly built glibc. Previously a tst-cleanup1 linked with
an older glibc would segfault when run with an affected glibc build.
Tested on x86_64 with no regressions.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/nptl/tcb-offsets.sym | 1 | ||||
| -rw-r--r-- | sysdeps/x86_64/nptl/tls.h | 5 |
2 files changed, 1 insertions, 5 deletions
diff --git a/sysdeps/x86_64/nptl/tcb-offsets.sym b/sysdeps/x86_64/nptl/tcb-offsets.sym index 03b6dba5c3..8a25c482cb 100644 --- a/sysdeps/x86_64/nptl/tcb-offsets.sym +++ b/sysdeps/x86_64/nptl/tcb-offsets.sym @@ -15,7 +15,6 @@ VGETCPU_CACHE_OFFSET offsetof (tcbhead_t, vgetcpu_cache) #ifndef __ASSUME_PRIVATE_FUTEX PRIVATE_FUTEX offsetof (tcbhead_t, private_futex) #endif -FEATURE_1_OFFSET offsetof (tcbhead_t, feature_1) -- Not strictly offsets, but these values are also used in the TCB. TCB_CANCELSTATE_BITMASK CANCELSTATE_BITMASK diff --git a/sysdeps/x86_64/nptl/tls.h b/sysdeps/x86_64/nptl/tls.h index 7f0b292f42..bdd02376f9 100644 --- a/sysdeps/x86_64/nptl/tls.h +++ b/sysdeps/x86_64/nptl/tls.h @@ -56,10 +56,7 @@ typedef struct # else int __glibc_reserved1; # endif - /* Bit 0: IBT. - Bit 1: SHSTK. - */ - unsigned int feature_1; + int __glibc_unused1; /* Reservation of some values for the TM ABI. */ void *__private_tm[4]; /* GCC split stack support. */ |