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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 15:24:40 +0200 |
| commit | a85abfa92220239cad0a8a6b0f2a223f5e6472a9 (patch) | |
| tree | 6ad58a6557e47419e84b58bd2cbfcd6c2c5aca14 | |
| parent | 60022fbfba872422993caf6130ad4b92e74bb356 (diff) | |
| download | glibc-a85abfa92220239cad0a8a6b0f2a223f5e6472a9.tar.gz glibc-a85abfa92220239cad0a8a6b0f2a223f5e6472a9.tar.xz glibc-a85abfa92220239cad0a8a6b0f2a223f5e6472a9.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 618515e80b..c2a91e1c2b 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. + 2016-06-21 Florian Weimer <fweimer@redhat.com> [BZ #20284] diff --git a/NEWS b/NEWS index 923468dd2e..a19f656448 100644 --- a/NEWS +++ b/NEWS @@ -7,6 +7,12 @@ using `glibc' in the "product" field. Version 2.22.1 +* 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) + * A stack-based buffer overflow was found in libresolv when invoked from libnss_dns, allowing specially crafted DNS responses to seize control of execution flow in the DNS client. The buffer overflow occurs in diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S index 24c72945c8..926b65af6f 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 |