diff mbox series

[110/165] fat: fix fat_ra_init() for data clusters == 0

Message ID 20200812013601.LbIXUhywg%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/165] percpu: return number of released bytes from pcpu_free_area() | expand

Commit Message

Andrew Morton Aug. 12, 2020, 1:36 a.m. UTC 
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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@mail.parknet.co.jp
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reported-by: syzbot+756199124937b31a9b7e@syzkaller.appspotmail.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/fat/fatent.c |    3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

--- 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);