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This patch adds an additional check for applications which change memory outside of the range allocated by malloc(), thus further hardening the malloc internals against both accidental and malicious overflows.
We should backport this additional upstream hardening:
commit 17f487b7afa7cd6c316040f3e6c86dc96b2eec30
Author: DJ Delorie <dj>
Date: Fri Mar 17 15:31:38 2017 -0400
Further harden glibc malloc metadata against 1-byte overflows.
Additional check for chunk_size == next->prev->chunk_size in unlink()
2017-03-17 Chris Evans <scarybeasts>
* malloc/malloc.c (unlink): Add consistency check between size and
next->prev->size, to further harden against 1-byte overflows.
This is on top of the hardening in bug 1326739.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2018:0805
We should backport this additional upstream hardening: commit 17f487b7afa7cd6c316040f3e6c86dc96b2eec30 Author: DJ Delorie <dj> Date: Fri Mar 17 15:31:38 2017 -0400 Further harden glibc malloc metadata against 1-byte overflows. Additional check for chunk_size == next->prev->chunk_size in unlink() 2017-03-17 Chris Evans <scarybeasts> * malloc/malloc.c (unlink): Add consistency check between size and next->prev->size, to further harden against 1-byte overflows. This is on top of the hardening in bug 1326739.