From 913eed83eda42012cde8a9a801c31b312545c098 Mon Sep 17 00:00:00 2001 From: Lukas Czerner Date: Wed, 21 Mar 2012 21:22:22 -0400 Subject: [PATCH] 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 Reviewed-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- fs/ext4/mballoc.c | 57 +++++++++++++++++++++++++---------------------- 1 file changed, 30 insertions(+), 27 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 23ec6a879b35..7d5a1e3a703a 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4914,11 +4914,11 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group, start = (e4b.bd_info->bb_first_free > start) ? e4b.bd_info->bb_first_free : start; - while (start < max) { - start = mb_find_next_zero_bit(bitmap, max, start); - if (start >= max) + while (start <= max) { + start = mb_find_next_zero_bit(bitmap, max + 1, start); + if (start > max) break; - next = mb_find_next_bit(bitmap, max, start); + next = mb_find_next_bit(bitmap, max + 1, start); if ((next - start) >= minblocks) { ext4_trim_extent(sb, start, @@ -4970,37 +4970,36 @@ out: int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) { struct ext4_group_info *grp; - ext4_group_t first_group, last_group; - ext4_group_t group, ngroups = ext4_get_groups_count(sb); + ext4_group_t group, first_group, last_group; ext4_grpblk_t cnt = 0, first_cluster, last_cluster; - uint64_t start, len, minlen, trimmed = 0; + uint64_t start, end, minlen, trimmed = 0; ext4_fsblk_t first_data_blk = le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block); + ext4_fsblk_t max_blks = ext4_blocks_count(EXT4_SB(sb)->s_es); int ret = 0; start = range->start >> sb->s_blocksize_bits; - len = range->len >> sb->s_blocksize_bits; + end = start + (range->len >> sb->s_blocksize_bits) - 1; minlen = range->minlen >> sb->s_blocksize_bits; - if (unlikely(minlen > EXT4_CLUSTERS_PER_GROUP(sb))) + if (unlikely(minlen > EXT4_CLUSTERS_PER_GROUP(sb)) || + unlikely(start >= max_blks)) return -EINVAL; - if (start + len <= first_data_blk) + if (end >= max_blks) + end = max_blks - 1; + if (end <= first_data_blk) goto out; - if (start < first_data_blk) { - len -= first_data_blk - start; + if (start < first_data_blk) start = first_data_blk; - } - /* Determine first and last group to examine based on start and len */ + /* Determine first and last group to examine based on start and end */ ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) start, &first_group, &first_cluster); - ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) (start + len), + ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) end, &last_group, &last_cluster); - last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group; - last_cluster = EXT4_CLUSTERS_PER_GROUP(sb); - if (first_group > last_group) - return -EINVAL; + /* end now represents the last cluster to discard in this group */ + end = EXT4_CLUSTERS_PER_GROUP(sb) - 1; for (group = first_group; group <= last_group; group++) { grp = ext4_get_group_info(sb, group); @@ -5012,24 +5011,28 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) } /* - * For all the groups except the last one, last block will - * always be EXT4_BLOCKS_PER_GROUP(sb), so we only need to - * change it for the last group in which case start + - * len < EXT4_BLOCKS_PER_GROUP(sb). + * For all the groups except the last one, last cluster will + * always be EXT4_CLUSTERS_PER_GROUP(sb)-1, so we only need to + * change it for the last group, note that last_cluster is + * already computed earlier by ext4_get_group_no_and_offset() */ - if (first_cluster + len < EXT4_CLUSTERS_PER_GROUP(sb)) - last_cluster = first_cluster + len; - len -= last_cluster - first_cluster; + if (group == last_group) + end = last_cluster; if (grp->bb_free >= minlen) { cnt = ext4_trim_all_free(sb, group, first_cluster, - last_cluster, minlen); + end, minlen); if (cnt < 0) { ret = cnt; break; } } trimmed += cnt; + + /* + * For every group except the first one, we are sure + * that the first cluster to discard will be cluster #0. + */ first_cluster = 0; } range->len = trimmed * sb->s_blocksize; -- 2.34.1