From: OGAWA Hirofumi Date: Wed, 12 Aug 2020 01:36:01 +0000 (-0700) Subject: fat: fix fat_ra_init() for data clusters == 0 X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a090a5a7d73f79a9ae2dcc6e60d89bfc6864a65a;p=linux.git 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. Reported-by: syzbot+756199124937b31a9b7e@syzkaller.appspotmail.com Signed-off-by: OGAWA Hirofumi Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/87mu462sv4.fsf@mail.parknet.co.jp Signed-off-by: Linus Torvalds --- 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);