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ext4: avoid a potential overflow in ext4_es_can_be_merged() 

Check the length of an extent to avoid a potential overflow in
ext4_es_can_be_merged().

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
This commit is contained in:
Zheng Liu 2013-03-10 20:48:59 -04:00 committed by Theodore Ts'o
parent 6ca470d7b5
commit bd384364c1
1 changed files with 16 additions and 6 deletions
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22
fs/ext4/extents_status.c
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@ -333,17 +333,27 @@ static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
static int ext4_es_can_be_merged(struct extent_status *es1, static int ext4_es_can_be_merged(struct extent_status *es1,
struct extent_status *es2) struct extent_status *es2)
{ {
if (es1->es_lblk + es1->es_len != es2->es_lblk)
return 0;
if (ext4_es_status(es1) != ext4_es_status(es2)) if (ext4_es_status(es1) != ext4_es_status(es2))
return 0; return 0;
if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) && if (((__u64) es1->es_len) + es2->es_len > 0xFFFFFFFFULL)
(ext4_es_pblock(es1) + es1->es_len != ext4_es_pblock(es2)))
return 0; return 0;
return 1; if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
return 0;
if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
(ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
return 1;
if (ext4_es_is_hole(es1))
return 1;
/* we need to check delayed extent is without unwritten status */
if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
return 1;
return 0;
} }
static struct extent_status * static struct extent_status *