commit 1ff22883b0b2f7a73eb2609ffe879c9fd96f6328
author David Howells <dhowells@redhat.com> Wed Oct 17 15:23:45 2018 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> Thu Oct 18 11:32:21 2018 +0200
tree 113747086e8d148ccd64a1cfcec97f10f558071e
parent 169b803397499be85bdd1e3d07d6f5e3d4bd669e

fscache: Fix incomplete initialisation of inline key space

The inline key in struct rxrpc_cookie is insufficiently initialized,
zeroing only 3 of the 4 slots, therefore an index_key_len between 13 and 15
bytes will end up hashing uninitialized memory because the memcpy only
partially fills the last buf[] element.

Fix this by clearing fscache_cookie objects on allocation rather than using
the slab constructor to initialise them.  We're going to pretty much fill
in the entire struct anyway, so bringing it into our dcache writably
shouldn't incur much overhead.

This removes the need to do clearance in fscache_set_key() (where we aren't
doing it correctly anyway).

Also, we don't need to set cookie->key_len in fscache_set_key() as we
already did it in the only caller, so remove that.

Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies")
Reported-by: syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com
Reported-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>