From: Phillip Lougher <phillip@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx Fixes: 93e72b3c612adcaca1 ("squashfs: migrate from ll_rw_block usage to BIO") Signed-off-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx> Reported-by: Bernd Amend <bernd.amend@xxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Adrien Schildknecht <adrien+dev@xxxxxxxxxxx> Cc: Guenter Roeck <groeck@xxxxxxxxxxxx> Cc: Daniel Rosenberg <drosen@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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))) { _
