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Message-Id: <1290694277-29462-1-git-send-email-lczerner@redhat.com>
Date: Thu, 25 Nov 2010 15:11:17 +0100
From: Lukas Czerner <lczerner@...hat.com>
To: tytso@....edu
Cc: linux-kernel@...r.kernel.org, sandeen@...hat.com,
lczerner@...hat.com
Subject: [PATCH] ext4: fix possible overflow in ext4_trim_fs()
When determining last group through ext4_get_group_no_and_offset() the
result may be wrong in cases when range->start and range-len are too
big, because it may overflow when summing up those two numbers.
Fix that by checking range->len and limit its value to
ext4_blocks_count(). This commit was tested by myself with expected
result.
Signed-off-by: Lukas Czerner <lczerner@...hat.com>
---
fs/ext4/mballoc.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 5b4d4e3..7b05d92 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4819,6 +4819,7 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
ext4_group_t group, ngroups = ext4_get_groups_count(sb);
ext4_grpblk_t cnt = 0, first_block, last_block;
uint64_t start, len, minlen, trimmed;
+ ext4_fsblk_t blocks_count = ext4_blocks_count(EXT4_SB(sb)->s_es);
int ret = 0;
start = range->start >> sb->s_blocksize_bits;
@@ -4826,6 +4827,9 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
minlen = range->minlen >> sb->s_blocksize_bits;
trimmed = 0;
+ if (len > blocks_count)
+ len = blocks_count - start;
+
if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))
return -EINVAL;
--
1.7.2.3
--
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