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| -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
@@ -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] @@ -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 |