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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2017-11-17 16:04:29 -0200
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2018-03-05 18:08:27 -0300
commit68448be208ee06e76665918b37b0a57e3e00c8b4 (patch)
tree07c9ed97d7afa4a6516db76079638e7329c12504 /ChangeLog
parent8d965cde7a2bc18a010325607f6f526db86cdaf0 (diff)
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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 'ChangeLog')
-rw-r--r--ChangeLog8
1 files changed, 8 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index e0639e93ec..f54496f8cb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2018-03-03  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	[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.
+
 2018-03-03  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
 	* scripts/check-installed-headers.sh: Ignore Hurd and Mach headers.