Message ID | 1330690318-22627-1-git-send-email-lczerner@redhat.com |
---|---|
State | Superseded, archived |
Headers | show |
On Fri 02-03-12 13:11:55, Lukas Czerner wrote: > 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. Looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > --- > v2: Squash the 'don't forget to discard last block in a group' into this one > since this is the commit which reveals the bug. > > fs/ext4/mballoc.c | 57 +++++++++++++++++++++++++++------------------------- > 1 files changed, 30 insertions(+), 27 deletions(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index cb990b2..16a3aeb 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -4971,11 +4971,11 @@ 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, > @@ -5027,37 +5027,36 @@ 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); > @@ -5069,24 +5068,28 @@ 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; > -- > 1.7.4.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Mar 05, 2012 at 01:37:57PM +0100, Jan Kara wrote: > On Fri 02-03-12 13:11:55, Lukas Czerner wrote: > > 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. > Looks good. You can add: > Reviewed-by: Jan Kara <jack@suse.cz> Thanks, applied. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index cb990b2..16a3aeb 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4971,11 +4971,11 @@ 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, @@ -5027,37 +5027,36 @@ 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); @@ -5069,24 +5068,28 @@ 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;
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> --- v2: Squash the 'don't forget to discard last block in a group' into this one since this is the commit which reveals the bug. fs/ext4/mballoc.c | 57 +++++++++++++++++++++++++++------------------------- 1 files changed, 30 insertions(+), 27 deletions(-)