From: Lukas Czerner <lczerner@redhat.com>
Date: Mon, 22 Oct 2012 22:01:19 +0000 (-0400)
Subject: ext4: Avoid underflow in ext4_trim_fs()
X-Git-Tag: v3.4.16~41
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=2807664df50419f56b596aa49da8a22102c0e0a3;p=karo-tx-linux.git

ext4: Avoid underflow in ext4_trim_fs()

commit 5de35e8d5c02d271c20e18337e01bc20e6ef472e upstream.

Currently if len argument in ext4_trim_fs() is smaller than one block,
the 'end' variable underflow. Avoid that by returning EINVAL if len is
smaller than file system block.

Also remove useless unlikely().

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 6b0a57eafb53..e77c4fe665a0 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4984,8 +4984,9 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
 	end = start + (range->len >> sb->s_blocksize_bits) - 1;
 	minlen = range->minlen >> sb->s_blocksize_bits;
 
-	if (unlikely(minlen > EXT4_CLUSTERS_PER_GROUP(sb)) ||
-	    unlikely(start >= max_blks))
+	if (minlen > EXT4_CLUSTERS_PER_GROUP(sb) ||
+	    start >= max_blks ||
+	    range->len < sb->s_blocksize)
 		return -EINVAL;
 	if (end >= max_blks)
 		end = max_blks - 1;