tree ef02603721d2737807868dbd8fc3dbecb6446a7c
parent 5391897e79bf8f2fb21b54e1f3b4486161de0388
author Sriram Rajagopalan <sriramr@arista.com> 1557530886 -0400
committer Todd Kjos <tkjos@google.com> 1572892455 -0800

ext4: zero out the unused memory region in the extent tree block

commit 592acbf16821288ecdc4192c47e3774a4c48bb64 upstream.

This commit zeroes out the unused memory region in the buffer_head
corresponding to the extent metablock after writing the extent header
and the corresponding extent node entries.

This is done to prevent random uninitialized data from getting into
the filesystem when the extent block is synced.

This fixes CVE-2019-11833.

Signed-off-by: Sriram Rajagopalan <sriramr@arista.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>