FPII-1860: pipe: Fix buffer offset after partially failed read
pipe: Fix buffer offset after partially failed read
Quoting the RHEL advisory:
> It was found that the fix for CVE-2015-1805 incorrectly kept buffer
> offset and buffer length in sync on a failed atomic read, potentially
> resulting in a pipe buffer state corruption. A local, unprivileged user
> could use this flaw to crash the system or leak kernel memory to user
> space. (CVE-2016-0774, Moderate)
The same flawed fix was applied to stable branches from 2.6.32.y to
3.14.y inclusive, and I was able to reproduce the issue on 3.2.y.
We need to give pipe_iov_copy_to_user() a separate offset variable
and only update the buffer offset if it succeeds.
--
We are cherry-picking the previously applied commit again, as it was
reverted by a faulty merge of an outdated upstream kernel release. See
commit 353bcb774c48c64c27ef4dc304b8cdb002e203e5.
Issue: SEC-2083
Change-Id: I988802f38acf40c7671fa0978880928b02d29b56
References: https://rhn.redhat.com/errata/RHSA-2016-0103.html
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit feae3ca2e5e1a8f44aa6290255d3d9709985d0b2)
(cherry picked from commit 37bfabf6e00b14ff3034989b1d2cf348b09f1228)
1 file changed