Commit 2910c59f authored by Phillip Lougher's avatar Phillip Lougher Committed by Linus Torvalds

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.

Fixes: 93e72b3c ("squashfs: migrate from ll_rw_block usage to BIO")
Reported-by: default avatarBernd Amend <bernd.amend@gmail.com>
Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
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>
Link: http://lkml.kernel.org/r/20200717195536.16069-1-phillip@squashfs.org.ukSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e57942c5
...@@ -175,7 +175,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length, ...@@ -175,7 +175,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
/* Extract the length of the metadata block */ /* Extract the length of the metadata block */
data = page_address(bvec->bv_page) + bvec->bv_offset; data = page_address(bvec->bv_page) + bvec->bv_offset;
length = data[offset]; length = data[offset];
if (offset <= bvec->bv_len - 1) { if (offset < bvec->bv_len - 1) {
length |= data[offset + 1] << 8; length |= data[offset + 1] << 8;
} else { } else {
if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
......
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