From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Subject: fat: fix fat_ra_init() for data clusters == 0 If data clusters == 0, fat_ra_init() calls the ->ent_blocknr() for the cluster beyond ->max_clusters. This checks the limit before initialization to suppress the warning. Link: http://lkml.kernel.org/r/87mu462sv4.fsf@xxxxxxxxxxxxxxxxxx Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Reported-by: syzbot+756199124937b31a9b7e@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/fat/fatent.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/fat/fatent.c~fat-fix-fat_ra_init-for-data-clusters-==-0 +++ a/fs/fat/fatent.c @@ -657,6 +657,9 @@ static void fat_ra_init(struct super_blo unsigned long ra_pages = sb->s_bdi->ra_pages; unsigned int reada_blocks; + if (fatent->entry >= ent_limit) + return; + if (ra_pages > sb->s_bdi->io_pages) ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); _
