From 6a14075325006dad7fef2f980f60dea8acb097a2 Mon Sep 17 00:00:00 2001 From: Yuezhang Mo Date: Mon, 17 Mar 2025 10:53:10 +0800 Subject: [PATCH] exfat: fix the infinite loop in exfat_find_last_cluster() [ Upstream commit b0522303f67255926b946aa66885a0104d1b2980 ] In exfat_find_last_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. If the number of clusters indicated by the file size is inconsistent with the cluster chain length, exfat_find_last_cluster() will return an error, so if this inconsistency is found, the traversal can be aborted without traversing to the EOF cluster. Reported-by: syzbot+f7d147e6db52b1e09dba@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f7d147e6db52b1e09dba Tested-by: syzbot+f7d147e6db52b1e09dba@syzkaller.appspotmail.com Fixes: 31023864e67a ("exfat: add fat entry operations") Signed-off-by: Yuezhang Mo Signed-off-by: Namjae Jeon Signed-off-by: Sasha Levin --- fs/exfat/fatent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c index 6f3651c6ca91e..8df5ad6ebb10c 100644 --- a/fs/exfat/fatent.c +++ b/fs/exfat/fatent.c @@ -265,7 +265,7 @@ int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain, clu = next; if (exfat_ent_get(sb, clu, &next)) return -EIO; - } while (next != EXFAT_EOF_CLUSTER); + } while (next != EXFAT_EOF_CLUSTER && count <= p_chain->size); if (p_chain->size != count) { exfat_fs_error(sb, -- 2.47.3