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ext4: fix start and len arguments handling in ext4_trim_fs()
The overflow can happen when we are calling get_group_no_and_offset() which stores the group number in the ext4_grpblk_t type which is actually int. However when the blocknr is big enough the group number might be bigger than ext4_grpblk_t resulting in overflow. This will most likely happen with FITRIM 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> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -4914,11 +4914,11 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
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start = (e4b.bd_info->bb_first_free > start) ?
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e4b.bd_info->bb_first_free : start;
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while (start < max) {
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start = mb_find_next_zero_bit(bitmap, max, start);
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if (start >= max)
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while (start <= max) {
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start = mb_find_next_zero_bit(bitmap, max + 1, start);
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if (start > max)
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break;
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next = mb_find_next_bit(bitmap, max, start);
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next = mb_find_next_bit(bitmap, max + 1, start);
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if ((next - start) >= minblocks) {
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ext4_trim_extent(sb, start,
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@ -4970,37 +4970,36 @@ out:
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int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
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{
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struct ext4_group_info *grp;
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ext4_group_t first_group, last_group;
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ext4_group_t group, ngroups = ext4_get_groups_count(sb);
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ext4_group_t group, first_group, last_group;
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ext4_grpblk_t cnt = 0, first_cluster, last_cluster;
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uint64_t start, len, minlen, trimmed = 0;
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uint64_t start, end, minlen, trimmed = 0;
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ext4_fsblk_t first_data_blk =
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le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
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ext4_fsblk_t max_blks = ext4_blocks_count(EXT4_SB(sb)->s_es);
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int ret = 0;
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start = range->start >> sb->s_blocksize_bits;
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len = range->len >> sb->s_blocksize_bits;
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end = start + (range->len >> sb->s_blocksize_bits) - 1;
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minlen = range->minlen >> sb->s_blocksize_bits;
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if (unlikely(minlen > EXT4_CLUSTERS_PER_GROUP(sb)))
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if (unlikely(minlen > EXT4_CLUSTERS_PER_GROUP(sb)) ||
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unlikely(start >= max_blks))
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return -EINVAL;
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if (start + len <= first_data_blk)
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if (end >= max_blks)
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end = max_blks - 1;
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if (end <= first_data_blk)
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goto out;
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if (start < first_data_blk) {
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len -= first_data_blk - start;
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if (start < first_data_blk)
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start = first_data_blk;
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}
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/* Determine first and last group to examine based on start and len */
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/* Determine first and last group to examine based on start and end */
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ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) start,
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&first_group, &first_cluster);
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ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) (start + len),
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ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) end,
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&last_group, &last_cluster);
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last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;
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last_cluster = EXT4_CLUSTERS_PER_GROUP(sb);
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if (first_group > last_group)
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return -EINVAL;
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/* end now represents the last cluster to discard in this group */
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end = EXT4_CLUSTERS_PER_GROUP(sb) - 1;
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for (group = first_group; group <= last_group; group++) {
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grp = ext4_get_group_info(sb, group);
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@ -5012,24 +5011,28 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
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}
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/*
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* For all the groups except the last one, last block will
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* always be EXT4_BLOCKS_PER_GROUP(sb), so we only need to
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* change it for the last group in which case start +
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* len < EXT4_BLOCKS_PER_GROUP(sb).
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* For all the groups except the last one, last cluster will
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* always be EXT4_CLUSTERS_PER_GROUP(sb)-1, so we only need to
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* change it for the last group, note that last_cluster is
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* already computed earlier by ext4_get_group_no_and_offset()
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*/
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if (first_cluster + len < EXT4_CLUSTERS_PER_GROUP(sb))
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last_cluster = first_cluster + len;
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len -= last_cluster - first_cluster;
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if (group == last_group)
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end = last_cluster;
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if (grp->bb_free >= minlen) {
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cnt = ext4_trim_all_free(sb, group, first_cluster,
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last_cluster, minlen);
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end, minlen);
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if (cnt < 0) {
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ret = cnt;
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break;
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}
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}
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trimmed += cnt;
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/*
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* For every group except the first one, we are sure
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* that the first cluster to discard will be cluster #0.
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*/
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first_cluster = 0;
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}
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range->len = trimmed * sb->s_blocksize;
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