The patch titled Subject: nilfs2: reject devices with insufficient block count has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-reject-devices-with-insufficient-block-count.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Ryusuke Konishi konishi.ryusuke@gmail.com Subject: nilfs2: reject devices with insufficient block count Date: Fri, 26 May 2023 11:13:32 +0900

The current sanity check for nilfs2 geometry information lacks checks for the number of segments stored in superblocks, so even for device images that have been destructively truncated or have an unusually high number of segments, the mount operation may succeed.

This causes out-of-bounds block I/O on file system block reads or log writes to the segments, the latter in particular causing "a_ops->writepages" to repeatedly fail, resulting in sync_inodes_sb() to hang.

Fix this issue by checking the number of segments stored in the superblock and avoiding mounting devices that can cause out-of-bounds accesses. To eliminate the possibility of overflow when calculating the number of blocks required for the device from the number of segments, this also adds a helper function to calculate the upper bound on the number of segments and inserts a check using it.

Link: https://lkml.kernel.org/r/20230526021332.3431-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+7d50f1e54a12ba3aeae2@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=7d50f1e54a12ba3aeae2 Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/nilfs2/the_nilfs.c | 43 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-)

--- a/fs/nilfs2/the_nilfs.c~nilfs2-reject-devices-with-insufficient-block-count +++ a/fs/nilfs2/the_nilfs.c @@ -405,6 +405,18 @@ unsigned long nilfs_nrsvsegs(struct the_ 100)); }

+/** + * nilfs_max_segment_count - calculate the maximum number of segments + * @nilfs: nilfs object + */ +static u64 nilfs_max_segment_count(struct the_nilfs *nilfs) +{ + u64 max_count = U64_MAX; + + do_div(max_count, nilfs->ns_blocks_per_segment); + return min_t(u64, max_count, ULONG_MAX); +} + void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs) { nilfs->ns_nsegments = nsegs; @@ -414,6 +426,8 @@ void nilfs_set_nsegments(struct the_nilf static int nilfs_store_disk_layout(struct the_nilfs *nilfs, struct nilfs_super_block *sbp) { + u64 nsegments, nblocks; + if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) { nilfs_err(nilfs->ns_sb, "unsupported revision (superblock rev.=%d.%d, current rev.=%d.%d). Please check the version of mkfs.nilfs(2).", @@ -457,7 +471,34 @@ static int nilfs_store_disk_layout(struc return -EINVAL; }

- nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments)); + nsegments = le64_to_cpu(sbp->s_nsegments); + if (nsegments > nilfs_max_segment_count(nilfs)) { + nilfs_err(nilfs->ns_sb, + "segment count %llu exceeds upper limit (%llu segments)", + (unsigned long long)nsegments, + (unsigned long long)nilfs_max_segment_count(nilfs)); + return -EINVAL; + } + + nblocks = sb_bdev_nr_blocks(nilfs->ns_sb); + if (nblocks) { + u64 min_block_count = nsegments * nilfs->ns_blocks_per_segment; + /* + * To avoid failing to mount early device images without a + * second superblock, exclude that block count from the + * "min_block_count" calculation. + */ + + if (nblocks < min_block_count) { + nilfs_err(nilfs->ns_sb, + "total number of segment blocks %llu exceeds device size (%llu blocks)", + (unsigned long long)min_block_count, + (unsigned long long)nblocks); + return -EINVAL; + } + } + + nilfs_set_nsegments(nilfs, nsegments); nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed); return 0; } _

Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-fix-incomplete-buffer-cleanup-in-nilfs_btnode_abort_change_key.patch nilfs2-fix-possible-out-of-bounds-segment-allocation-in-resize-ioctl.patch nilfs2-reject-devices-with-insufficient-block-count.patch