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83d6db8187
This patch fixes the i386 sa_restorer field initialization for sigaction
syscall for kernel with vDSO. As described in bug report, i386 Linux
(and compat on x86_64) interprets SA_RESTORER clear with nonzero
sa_restorer as a request for stack switching if the SS segment is 'funny'.
This means that anything that tries to mix glibc's signal handling with
segmentation (for instance through modify_ldt syscall) is randomly broken
depending on what values lands in sa_restorer.
The testcase added is based on Linux test tools/testing/selftests/x86/ldt_gdt.c,
more specifically in do_multicpu_tests function. The main changes are:
- C11 atomics instead of plain access.
- Remove x86_64 support which simplifies the syscall handling and fallbacks.
- Replicate only the test required to trigger the issue.
Checked on i686-linux-gnu.
[BZ #21269]
* sysdeps/unix/sysv/linux/i386/Makefile (tests): Add tst-bz21269.
* sysdeps/unix/sysv/linux/i386/sigaction.c (SET_SA_RESTORER): Clear
sa_restorer for vDSO case.
* sysdeps/unix/sysv/linux/i386/tst-bz21269.c: New file.
(cherry picked from commit
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| .. | ||
| alpha | ||
| arm | ||
| bsd | ||
| i386 | ||
| inet | ||
| mips | ||
| powerpc | ||
| sh | ||
| sysv/linux | ||
| x86_64 | ||
| clock_gettime.c | ||
| clock_nanosleep.c | ||
| clock_settime.c | ||
| confstr.h | ||
| get_child_max.c | ||
| getlogin_r.c | ||
| getlogin.c | ||
| getpagesize.c | ||
| grantpt.c | ||
| ifreq.c | ||
| Implies | ||
| make-syscalls.sh | ||
| Makefile | ||
| s-proto-cancel.S | ||
| s-proto.S | ||
| setxid.h | ||
| sockatmark.c | ||
| stime.c | ||
| syscall-template.S | ||
| syscall.S | ||
| syscalls.list | ||
| sysdep.h | ||