6.12-stable review patch. If anyone has any objections, please let me know.
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From: Yuezhang Mo Yuezhang.Mo@sony.com
[ Upstream commit a5324b3a488d883aa2d42f72260054e87d0940a0 ]
In __exfat_free_cluster(), the cluster chain is traversed until the EOF cluster. If the cluster chain includes a loop due to file system corruption, the EOF cluster cannot be traversed, resulting in an infinite loop.
This commit uses the total number of clusters to prevent this infinite loop.
Reported-by: syzbot+1de5a37cb85a2d536330@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1de5a37cb85a2d536330 Tested-by: syzbot+1de5a37cb85a2d536330@syzkaller.appspotmail.com Fixes: 31023864e67a ("exfat: add fat entry operations") Signed-off-by: Yuezhang Mo Yuezhang.Mo@sony.com Reviewed-by: Sungjong Seo sj1557.seo@samsung.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/exfat/fatent.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c index 773c320d68f3..9e5492ac409b 100644 --- a/fs/exfat/fatent.c +++ b/fs/exfat/fatent.c @@ -216,6 +216,16 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
if (err) goto dec_used_clus; + + if (num_clusters >= sbi->num_clusters - EXFAT_FIRST_CLUSTER) { + /* + * The cluster chain includes a loop, scan the + * bitmap to get the number of used clusters. + */ + exfat_count_used_clusters(sb, &sbi->used_clusters); + + return 0; + } } while (clu != EXFAT_EOF_CLUSTER); }