From: OGAWA Hirofumi hirofumi@mail.parknet.co.jp
[ Upstream commit a090a5a7d73f79a9ae2dcc6e60d89bfc6864a65a ]
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.
Reported-by: syzbot+756199124937b31a9b7e@syzkaller.appspotmail.com Signed-off-by: OGAWA Hirofumi hirofumi@mail.parknet.co.jp Signed-off-by: Andrew Morton akpm@linux-foundation.org Link: http://lkml.kernel.org/r/87mu462sv4.fsf@mail.parknet.co.jp Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/fat/fatent.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c index bbfe18c074179..f7e3304b78029 100644 --- a/fs/fat/fatent.c +++ b/fs/fat/fatent.c @@ -657,6 +657,9 @@ static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra, 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);