From: Michael Halcrow <mhalcrow@google.com>
Date: Wed, 26 Nov 2014 17:09:16 +0000 (-0800)
Subject: eCryptfs: Remove buggy and unnecessary write in file name decode routine
X-Git-Tag: v3.2.67~113
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=f2d130454e46c3989af1b4f882b6a666d24fa2e0;hp=3ca74798ef821cc6558fc04f083edc98afa28b2a

eCryptfs: Remove buggy and unnecessary write in file name decode routine

commit 942080643bce061c3dd9d5718d3b745dcb39a8bc upstream.

Dmitry Chernenkov used KASAN to discover that eCryptfs writes past the
end of the allocated buffer during encrypted filename decoding. This
fix corrects the issue by getting rid of the unnecessary 0 write when
the current bit offset is 2.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Reported-by: Dmitry Chernenkov <dmitryc@google.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 68b19ab04811..dceedecfb8aa 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -2038,7 +2038,6 @@ ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
 			break;
 		case 2:
 			dst[dst_byte_offset++] |= (src_byte);
-			dst[dst_byte_offset] = 0;
 			current_bit_offset = 0;
 			break;
 		}