[SRU][T][PATCH 0/1] CVE-2016-10741 - Local DoS in XFS

[Hui Wang]

https://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-10741.html

In the Linux kernel before 4.9.3, fs/xfs/xfs_aops.c allows local users to
cause a denial of service (system crash) because there is a race condition
between direct and memory-mapped I/O (associated with a hole) that is
handled with BUG_ON instead of an I/O failure.

This issue is only for trusty kernel. The original patch context is different
from the trusty kernel, I backported this patch rather than cherry-picked.

I think the backport is safe since the logic is same as the original
patch (if there are  both direct and mapped-IO access for a file at the same
time, don't BUG_ON() unconditionally, instead we will return EIO or
WARN_ON_ONCE() conditionally).

building test pass.

I generated a xfs filesytem based on a file (dd, mount and mkfs.xfs) and did
some basic file operations (generate a new file, write sth in
this file, read out from this file, delete this file), everthing
works fine as before.

Brian Foster (1):
  xfs: don't BUG() on mixed direct and mapped I/O

 fs/xfs/xfs_aops.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

-- 
2.17.1