From 969a1a2d5c581d958ce5da37e827ed2217aac17a Mon Sep 17 00:00:00 2001
From: Stijn Tintel <stijn@linux-ipv6.be>
Date: Thu, 13 May 2021 23:08:47 +0300
Subject: bcachefs: avoid out-of-bounds in split_devs

Calling mount with an empty source string causes an out-of-bounds error
in split_devs. Check the length of the source string to avoid this.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>
---
 fs/bcachefs/fs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 3161760050c9..6f1512176c4d 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -30,6 +30,7 @@
 #include <linux/posix_acl.h>
 #include <linux/random.h>
 #include <linux/statfs.h>
+#include <linux/string.h>
 #include <linux/xattr.h>
 
 static struct kmem_cache *bch2_inode_cache;
@@ -1310,6 +1311,9 @@ static char **split_devs(const char *_dev_name, unsigned *nr)
 	char *dev_name = NULL, **devs = NULL, *s;
 	size_t i, nr_devs = 0;
 
+	if (strlen(_dev_name) == 0)
+		return NULL;
+
 	dev_name = kstrdup(_dev_name, GFP_KERNEL);
 	if (!dev_name)
 		return NULL;
-- 
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