From: Baokun Li libaokun1@huawei.com

stable inclusion from stable-v4.19.273 commit b4fbb89d722cbb16beaaea234b7230faaaf68c71 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9E2F9 CVE: CVE-2024-26704

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=l...

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commit 55583e899a5357308274601364741a83e78d6ac4 upstream.

In ext4_move_extents(), moved_len is only updated when all moves are successfully executed, and only discards orig_inode and donor_inode preallocations when moved_len is not zero. When the loop fails to exit after successfully moving some extents, moved_len is not updated and remains at 0, so it does not discard the preallocations.

If the moved extents overlap with the preallocated extents, the overlapped extents are freed twice in ext4_mb_release_inode_pa() and ext4_process_freed_data() (as described in commit 94d7c16cbbbd ("ext4: Fix double-free of blocks with EXT4_IOC_MOVE_EXT")), and bb_free is incremented twice. Hence when trim is executed, a zero-division bug is triggered in mb_update_avg_fragment_size() because bb_free is not zero and bb_fragments is zero.

Therefore, update move_len after each extent move to avoid the issue.

Reported-by: Wei Chen harperchen1110@gmail.com Reported-by: xingwei lee xrivendell7@gmail.com Closes: https://lore.kernel.org/r/CAO4mrferzqBUnCag8R3m2zf897ts9UEuhjFQGPtODT92rYyR2... Fixes: fcf6b1b729bc ("ext4: refactor ext4_move_extents code base") CC: stable@vger.kernel.org # 3.18 Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20240104142040.2835097-2-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Long Li leo.lilong@huawei.com --- fs/ext4/move_extent.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index 97512df281e3..4616d41216f3 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -618,6 +618,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, goto out; o_end = o_start + len;

+ *moved_len = 0; while (o_start < o_end) { struct ext4_extent *ex; ext4_lblk_t cur_blk, next_blk; @@ -673,7 +674,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, */ ext4_double_up_write_data_sem(orig_inode, donor_inode); /* Swap original branches with new branches */ - move_extent_per_page(o_filp, donor_inode, + *moved_len += move_extent_per_page(o_filp, donor_inode, orig_page_index, donor_page_index, offset_in_page, cur_len, unwritten, &ret); @@ -683,9 +684,6 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk, o_start += cur_len; d_start += cur_len; } - *moved_len = o_start - orig_blk; - if (*moved_len > len) - *moved_len = len;

out: if (*moved_len) {