smb: client: fix heap overflow in cifs_do_set_acl()

cifs_set_acl() validates ACL size using posix_acl_xattr_size():

        4 + (count * 8)  // 4-byte header + 8 bytes per ACE

cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS
wire format into the same buffer:

        6 + (count * 10)  // 6-byte header + 10 bytes per ACE

An ACL that passes the xattr-based check in cifs_set_acl() can
overflow the heap when posix_acl_to_cifs() writes the larger CIFS
format.

Validate the CIFS format size against the remaining buffer space and
USHRT_MAX before converting--data_count is __u16, so sizes above
USHRT_MAX truncate the on-wire packet length, causing the server to
apply a partial ACL.  Replace MaxDataCount = 1000 with
min(CIFSMaxBufSize, USHRT_MAX).

Fixes: dc1af4c4b4721 ("cifs: implement set acl method")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>

0 files changed, 0 insertions, 0 deletions