From: Yuezhang Mo Yuezhang.Mo@sony.com
commit 706fdcac002316893434d753be8cfb549fe1d40d upstream.
Since seekdir() does not check whether the position is valid, the position may exceed the size of the directory. We found that for a directory with discontinuous clusters, if the position exceeds the size of the directory and the excess size is greater than or equal to the cluster size, exfat_readdir() will return -EIO, causing a file system error and making the file system unavailable.
Reproduce this bug by:
seekdir(dir, dir_size + cluster_size); dirent = readdir(dir);
The following log will be printed if mount with 'errors=remount-ro'.
[11166.712896] exFAT-fs (sdb1): error, invalid access to FAT (entry 0xffffffff) [11166.712905] exFAT-fs (sdb1): Filesystem has been set read-only
Fixes: 1e5654de0f51 ("exfat: handle wrong stream entry size in exfat_readdir()") Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Yuezhang Mo Yuezhang.Mo@sony.com Reviewed-by: Andy Wu Andy.Wu@sony.com Reviewed-by: Aoyama Wataru wataru.aoyama@sony.com Reviewed-by: Sungjong Seo sj1557.seo@samsung.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/exfat/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -103,7 +103,7 @@ static int exfat_readdir(struct inode *i clu.dir = ei->hint_bmap.clu; }
- while (clu_offset > 0) { + while (clu_offset > 0 && clu.dir != EXFAT_EOF_CLUSTER) { if (exfat_get_next_cluster(sb, &(clu.dir))) return -EIO;