From 9f586fff6574f6ecbf323f92d44ffaf0d96225fe Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Tue, 14 Nov 2017 09:59:54 -0500
Subject: [PATCH] dax: fix general protection fault in dax_alloc_inode
Git-commit: 9f586fff6574f6ecbf323f92d44ffaf0d96225fe
Patch-mainline: v4.15-rc1
References: bsc#1052766
Don't crash in case of allocation failure in dax_alloc_inode.
syzkaller hit the following crash on e4880bc5dfb1
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
[..]
RIP: 0010:dax_alloc_inode+0x3b/0x70 drivers/dax/super.c:348
Call Trace:
alloc_inode+0x65/0x180 fs/inode.c:208
new_inode_pseudo+0x69/0x190 fs/inode.c:890
new_inode+0x1c/0x40 fs/inode.c:919
mount_pseudo_xattr+0x288/0x560 fs/libfs.c:261
mount_pseudo include/linux/fs.h:2137 [inline]
dax_mount+0x2e/0x40 drivers/dax/super.c:388
mount_fs+0x66/0x2d0 fs/super.c:1223
Cc: <stable@vger.kernel.org>
Fixes: 7b6be8444e0f ("dax: refactor dax-fs into a generic provider...")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
---
drivers/dax/super.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 69329e3954ea..3ec804672601 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -341,6 +341,9 @@ static struct inode *dax_alloc_inode(struct super_block *sb)
struct inode *inode;
dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
+ if (!dax_dev)
+ return NULL;
+
inode = &dax_dev->inode;
inode->i_rdev = 0;
return inode;
--
2.12.3