[ 3.5.yuz extended stable ] Patch "ext4: Avoid underflow in ext4_trim_fs()" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ext4: Avoid underflow in ext4_trim_fs()

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 72b839359359aa6e2e349a6481f3268aad009e76 Mon Sep 17 00:00:00 2001
From: Lukas Czerner <lczerner at redhat.com>
Date: Mon, 22 Oct 2012 18:01:19 -0400
Subject: [PATCH] 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 at redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/ext4/mballoc.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 70f97a5..af848bb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4983,8 +4983,9 @@ 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;
--
1.7.9.5