5.10-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 fee873761bd978d077d8c55334b4966ac4cb7b59 ]
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 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/dir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index 4543013ac048..2c2ac7fca327 100644 --- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -125,7 +125,7 @@ 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) { @@ -185,6 +185,7 @@ 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;