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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 11:38:28 +0200 |
| commit | 72450627ba8a173366265af550115de951f148c9 (patch) | |
| tree | 8b284bbad5b5cd0b2fa5b127f8852dfe4b2c11e7 | |
| parent | e2e4984ad62330fa1d328d9eeb0a3e42620825b6 (diff) | |
| download | glibc-72450627ba8a173366265af550115de951f148c9.tar.gz glibc-72450627ba8a173366265af550115de951f148c9.tar.xz glibc-72450627ba8a173366265af550115de951f148c9.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 | 11 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/setcontext.S | 7 |
3 files changed, 24 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 9dfd24dae5..734e34b554 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 b0447e7169..4a042dbe2b 100644 --- a/NEWS +++ b/NEWS @@ -5,6 +5,17 @@ See the end for copying conditions. Please send GNU C library bug reports via <http://sourceware.org/bugzilla/> using `glibc' in the "product" field. +Version 2.24.1 + +Security related changes: + +* 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) + + Version 2.24 * The minimum Linux kernel version that this version of the GNU C Library 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 |