From: Yuezhang Mo Date: Fri, 13 Dec 2024 05:08:37 +0000 (+0800) Subject: exfat: fix the infinite loop in exfat_readdir() X-Git-Tag: v6.13-rc7~36^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fee873761bd978d077d8c55334b4966ac4cb7b59;p=thirdparty%2Flinux.git exfat: fix the infinite loop in exfat_readdir() If the file system is corrupted so that a cluster is linked to itself in the cluster chain, and there is an unused directory entry in the cluster, 'dentry' will not be incremented, causing condition 'dentry < max_dentries' unable to prevent an infinite loop. This infinite loop causes s_lock not to be released, and other tasks will hang, such as exfat_sync_fs(). This commit stops traversing the cluster chain when there is unused directory entry in the cluster to avoid this infinite loop. Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc Tested-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com Fixes: ca06197382bd ("exfat: add directory operations") Signed-off-by: Yuezhang Mo Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon --- diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index fe0a9b8a0cd07..3103b932b6746 100644 --- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -122,7 +122,7 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent type = exfat_get_entry_type(ep); if (type == TYPE_UNUSED) { brelse(bh); - break; + goto out; } if (type != TYPE_FILE && type != TYPE_DIR) { @@ -170,6 +170,7 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent } } +out: dir_entry->namebuf.lfn[0] = '\0'; *cpos = EXFAT_DEN_TO_B(dentry); return 0;