eCryptfs: Sanitize write counts of /dev/ecryptfs
commitcdce30003c234575bbcfddb0980adc04b82408c7
authorTyler Hicks <tyhicks@canonical.com>
Thu, 12 Jan 2012 10:30:44 +0000 (12 11:30 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 3 Feb 2012 17:18:50 +0000 (3 09:18 -0800)
tree2ee44e04d22b978baba5bac720ba48f0162ff70a
parenta3c9ccb3e13812e13be045a97ab309a4e23d9ac4
eCryptfs: Sanitize write counts of /dev/ecryptfs

commit db10e556518eb9d21ee92ff944530d84349684f4 upstream.

A malicious count value specified when writing to /dev/ecryptfs may
result in a a very large kernel memory allocation.

This patch peeks at the specified packet payload size, adds that to the
size of the packet headers and compares the result with the write count
value. The resulting maximum memory allocation size is approximately 532
bytes.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/ecryptfs/miscdev.c