[PATCH AUTOSEL 5.8 26/27] fat: fix fat_ra_init() for data clusters == 0
From: Sasha Levin <sashal@kernel.org>
Date: 2020-08-20 00:12:36
Also in:
lkml
Subsystem:
filesystems (vfs and infrastructure), the rest, vfat/fat/msdos filesystem · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds, OGAWA Hirofumi
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);
--
2.25.1