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ext3: fix start and len arguments handling in ext3_trim_fs()

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The overflow might happen when passing blocknr into
ext3_get_group_no_and_offset(), because it expects type ext3_fsblk_t
which might be smaller than uint64_t. This will most likely happen when
calling FITRIM with the default argument len = ULLONG_MAX.

Fix this by using "end" variable instead of "start+len" as it is easier
to get right and specifically check that the end is not beyond the end
of the file system, so we are sure that the result of
get_group_no_and_offset() will not overflow. Otherwise truncate it to
the size of the file system.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Lukas Czerner 2012-03-02 13:09:05 +01:00 committed by Jan Kara
parent a0391a3ae9
commit e703c20613
1 changed files with 39 additions and 38 deletions
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77
fs/ext3/balloc.c
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@ -1973,7 +1973,7 @@ static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb,
sbi = EXT3_SB(sb); sbi = EXT3_SB(sb);
/* Walk through the whole group */ /* Walk through the whole group */
while (start < max) { while (start <= max) {
start = bitmap_search_next_usable_block(start, bitmap_bh, max); start = bitmap_search_next_usable_block(start, bitmap_bh, max);
if (start < 0) if (start < 0)
break; break;
@ -1983,7 +1983,7 @@ static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb,
* Allocate contiguous free extents by setting bits in the * Allocate contiguous free extents by setting bits in the
* block bitmap * block bitmap
*/ */
while (next < max while (next <= max
&& claim_block(sb_bgl_lock(sbi, group), && claim_block(sb_bgl_lock(sbi, group),
next, bitmap_bh)) { next, bitmap_bh)) {
next++; next++;
@ -2094,73 +2094,74 @@ err_out:
*/ */
int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range) int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
{ {
ext3_grpblk_t last_block, first_block, free_blocks; ext3_grpblk_t last_block, first_block;
unsigned long first_group, last_group; unsigned long group, first_group, last_group;
unsigned long group, ngroups;
struct ext3_group_desc *gdp; struct ext3_group_desc *gdp;
struct ext3_super_block *es = EXT3_SB(sb)->s_es; struct ext3_super_block *es = EXT3_SB(sb)->s_es;
uint64_t start, len, minlen, trimmed; uint64_t start, minlen, end, trimmed = 0;
ext3_fsblk_t first_data_blk =
le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block);
ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count); ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);
int ret = 0; int ret = 0;
start = (range->start >> sb->s_blocksize_bits) + start = range->start >> sb->s_blocksize_bits;
le32_to_cpu(es->s_first_data_block); end = start + (range->len >> sb->s_blocksize_bits) - 1;
len = range->len >> sb->s_blocksize_bits;
minlen = range->minlen >> sb->s_blocksize_bits; minlen = range->minlen >> sb->s_blocksize_bits;
trimmed = 0;
if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb))) if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb)) ||
unlikely(start >= max_blks))
return -EINVAL; return -EINVAL;
if (start >= max_blks) if (end >= max_blks)
return -EINVAL; end = max_blks - 1;
if (start + len > max_blks) if (end <= first_data_blk)
len = max_blks - start; goto out;
if (start < first_data_blk)
start = first_data_blk;
ngroups = EXT3_SB(sb)->s_groups_count;
smp_rmb(); smp_rmb();
/* Determine first and last group to examine based on start and len */ /* Determine first and last group to examine based on start and len */
ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start, ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,
&first_group, &first_block); &first_group, &first_block);
ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) (start + len), ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) end,
&last_group, &last_block); &last_group, &last_block);
last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;
last_block = EXT3_BLOCKS_PER_GROUP(sb);
if (first_group > last_group) /* end now represents the last block to discard in this group */
return -EINVAL; end = EXT3_BLOCKS_PER_GROUP(sb) - 1;
for (group = first_group; group <= last_group; group++) { for (group = first_group; group <= last_group; group++) {
gdp = ext3_get_group_desc(sb, group, NULL); gdp = ext3_get_group_desc(sb, group, NULL);
if (!gdp) if (!gdp)
break; break;
free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
if (free_blocks < minlen)
continue;
/* /*
* For all the groups except the last one, last block will * For all the groups except the last one, last block will
* always be EXT3_BLOCKS_PER_GROUP(sb), so we only need to * always be EXT3_BLOCKS_PER_GROUP(sb)-1, so we only need to
* change it for the last group in which case first_block + * change it for the last group, note that last_block is
* len < EXT3_BLOCKS_PER_GROUP(sb). * already computed earlier by ext3_get_group_no_and_offset()
*/ */
if (first_block + len < EXT3_BLOCKS_PER_GROUP(sb)) if (group == last_group)
last_block = first_block + len; end = last_block;
len -= last_block - first_block;
ret = ext3_trim_all_free(sb, group, first_block, if (le16_to_cpu(gdp->bg_free_blocks_count) >= minlen) {
last_block, minlen); ret = ext3_trim_all_free(sb, group, first_block,
if (ret < 0) end, minlen);
break; if (ret < 0)
break;
trimmed += ret;
}
trimmed += ret; /*
* For every group except the first one, we are sure
* that the first block to discard will be block #0.
*/
first_block = 0; first_block = 0;
} }
if (ret >= 0) if (ret > 0)
ret = 0; ret = 0;
range->len = trimmed * sb->s_blocksize;
out:
range->len = trimmed * sb->s_blocksize;
return ret; return ret;
} }