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| author | Andreas Schwab <schwab@suse.de> | 2016-08-18 11:38:28 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2016-08-18 13:00:06 +0200 |
| commit | 23446cad92195d8c50092410b4f72ca7f6d1d2f1 (patch) | |
| tree | 4857bc2e5096f8a5f8665ef087e6ee37ffbd842e | |
| parent | 3a97372dbe373e02cb1d4053a449d246c32cf454 (diff) | |
| download | glibc-23446cad92195d8c50092410b4f72ca7f6d1d2f1.tar.gz glibc-23446cad92195d8c50092410b4f72ca7f6d1d2f1.tar.xz glibc-23446cad92195d8c50092410b4f72ca7f6d1d2f1.zip | |
arm: mark __startcontext as .cantunwind (bug 20435)
__startcontext marks the bottom of the call stack of the contexts created by makecontext. (cherry picked from commit 9e2ff6c9cc54c0b4402b8d49e4abe7000fde7617) Also includes the NEWS update, cherry-picked from commits 056dd72af83f5459ce6d545a49dea6dba7d635dc and 4d047efdbc55b0d68947cde682e5363d16a66294.
| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | NEWS | 6 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/setcontext.S | 7 |
3 files changed, 19 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 0598caa614..178aab2bbc 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2016-08-15 Andreas Schwab <schwab@suse.de> + + [BZ #20435] + * sysdeps/unix/sysv/linux/arm/setcontext.S (__startcontext): Mark + as .cantunwind. + 2016-08-17 Florian Weimer <fweimer@redhat.com> [BZ #20452] diff --git a/NEWS b/NEWS index 07f3fe8569..e03e9f1f3f 100644 --- a/NEWS +++ b/NEWS @@ -22,6 +22,12 @@ Security related changes: flooded with crafted ICMP and UDP messages. Reported by Aldy Hernandez' alloca plugin for GCC. (CVE-2016-4429) +* On ARM EABI (32-bit), generating a backtrace for execution contexts which + have been created with makecontext could fail to terminate due to a + missing .cantunwind annotation. This has been observed to lead to a hang + (denial of service) in some Go applications compiled with gccgo. Reported + by Andreas Schwab. (CVE-2016-6323) + The following bugs are resolved with this release: [19679] gcc-4.9.3 C++ exception handling broken due to unaligned stack diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S index 603e508858..d1f168fece 100644 --- a/sysdeps/unix/sysv/linux/arm/setcontext.S +++ b/sysdeps/unix/sysv/linux/arm/setcontext.S @@ -86,12 +86,19 @@ weak_alias(__setcontext, setcontext) /* Called when a makecontext() context returns. Start the context in R4 or fall through to exit(). */ + /* Unwind descriptors are looked up based on PC - 2, so we have to + make sure to mark the instruction preceding the __startcontext + label as .cantunwind. */ + .fnstart + .cantunwind + nop ENTRY(__startcontext) movs r0, r4 bne PLTJMP(__setcontext) @ New context was 0 - exit b PLTJMP(HIDDEN_JUMPTARGET(exit)) + .fnend END(__startcontext) #ifdef PIC |