+ squashfs-fix-length-field-overlap-check-in-metadata-reading.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: squashfs: fix length field overlap check in metadata reading
has been added to the -mm tree.  Its filename is
     squashfs-fix-length-field-overlap-check-in-metadata-reading.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/squashfs-fix-length-field-overlap-check-in-metadata-reading.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/squashfs-fix-length-field-overlap-check-in-metadata-reading.patch

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------------------------------------------------------
From: Phillip Lougher <phillip@squashfs.org.uk>
Subject: squashfs: fix length field overlap check in metadata reading

This is a regression introduced by the "migrate from ll_rw_block usage to
BIO" patch.

Squashfs packs structures on byte boundaries, and due to that the length
field (of the metadata block) may not be fully in the current block.  The
new code rewrote and introduced a faulty check for that edge case.

Link: http://lkml.kernel.org/r/20200717195536.16069-1-phillip@squashfs.org.uk
Fixes: 93e72b3c612adcaca1 ("squashfs: migrate from ll_rw_block usage to BIO")
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: Bernd Amend <bernd.amend@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Adrien Schildknecht <adrien+dev@schischi.me>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/squashfs/block.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/squashfs/block.c~squashfs-fix-length-field-overlap-check-in-metadata-reading
+++ a/fs/squashfs/block.c
@@ -175,7 +175,7 @@ int squashfs_read_data(struct super_bloc
 		/* Extract the length of the metadata block */
 		data = page_address(bvec->bv_page) + bvec->bv_offset;
 		length = data[offset];
-		if (offset <= bvec->bv_len - 1) {
+		if (offset < bvec->bv_len - 1) {
 			length |= data[offset + 1] << 8;
 		} else {
 			if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
_

Patches currently in -mm which might be from phillip@squashfs.org.uk are

squashfs-fix-length-field-overlap-check-in-metadata-reading.patch