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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2017-11-17 16:04:29 -0200 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2018-03-05 18:08:27 -0300 |
| commit | 68448be208ee06e76665918b37b0a57e3e00c8b4 (patch) | |
| tree | 07c9ed97d7afa4a6516db76079638e7329c12504 /sysdeps/unix/sysv/linux/i386/sigaction.c | |
| parent | 8d965cde7a2bc18a010325607f6f526db86cdaf0 (diff) | |
| download | glibc-68448be208ee06e76665918b37b0a57e3e00c8b4.tar.gz glibc-68448be208ee06e76665918b37b0a57e3e00c8b4.tar.xz glibc-68448be208ee06e76665918b37b0a57e3e00c8b4.zip | |
i386: Fix i386 sigaction sa_restorer initialization (BZ#21269)
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.
Diffstat (limited to 'sysdeps/unix/sysv/linux/i386/sigaction.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/i386/sigaction.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/sysdeps/unix/sysv/linux/i386/sigaction.c b/sysdeps/unix/sysv/linux/i386/sigaction.c index a5eb9e0d3e..177ff60ee6 100644 --- a/sysdeps/unix/sysv/linux/i386/sigaction.c +++ b/sysdeps/unix/sysv/linux/i386/sigaction.c @@ -42,7 +42,6 @@ extern void restore_rt (void) asm ("__restore_rt") attribute_hidden; #endif extern void restore (void) asm ("__restore") attribute_hidden; - /* If ACT is not NULL, change the action for SIG to *ACT. If OACT is not NULL, put the old action for SIG in *OACT. */ int @@ -65,6 +64,8 @@ __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact) kact.sa_restorer = ((act->sa_flags & SA_SIGINFO) ? &restore_rt : &restore); } + else + kact.sa_restorer = NULL; } /* XXX The size argument hopefully will have to be changed to the |