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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@redhat.com>
This commit is contained in:
Lukas Czerner 2011-01-10 12:04:55 -05:00 committed by Theodore Ts'o
parent b72143ab3e
commit 4f531501e4
1 changed files with 6 additions and 0 deletions
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6
fs/ext4/mballoc.c
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@ -4819,6 +4819,7 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
{
struct ext4_buddy e4b;
ext4_fsblk_t blocks_count = ext4_blocks_count(EXT4_SB(sb)->s_es);
ext4_group_t first_group, last_group;
ext4_group_t group, ngroups = ext4_get_groups_count(sb);
ext4_grpblk_t cnt = 0, first_block, last_block;
@ -4830,6 +4831,11 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
minlen = range->minlen >> sb->s_blocksize_bits;
trimmed = 0;
if (start >= blocks_count)
return -EINVAL;
if (start + len > blocks_count)
len = blocks_count - start;
if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))
return -EINVAL;