5.15-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 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 Yuezhang.Mo@sony.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 9c116a58544da..c5f6015a947ce 100644 --- a/fs/exfat/fatent.c +++ b/fs/exfat/fatent.c @@ -264,7 +264,7 @@ 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,