From 2910c59fd0423f87aca3a669b156a2325da63745 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Thu, 23 Jul 2020 21:15:40 -0700 Subject: [PATCH] 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: 93e72b3c612adcaca1 ("squashfs: migrate from ll_rw_block usage to BIO") Reported-by: Bernd Amend Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Cc: Christoph Hellwig Cc: Adrien Schildknecht Cc: Guenter Roeck Cc: Daniel Rosenberg Link: http://lkml.kernel.org/r/20200717195536.16069-1-phillip@squashfs.org.uk Signed-off-by: Linus Torvalds --- fs/squashfs/block.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c index 64f61330564a..76bb1c846845 100644 --- a/fs/squashfs/block.c +++ b/fs/squashfs/block.c @@ -175,7 +175,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length, /* 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))) {