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From:   Chao Yu <chao@kernel.org>
To:     linux-mm@kvack.org
Cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        chao@kernel.org, jaegeuk@kernel.org, Chao Yu <chao.yu@oppo.com>,
        stable@kernel.org,
        syzbot+81684812ea68216e08c5@syzkaller.appspotmail.com
Subject: [PATCH] mm/slub: fix to return errno if kmalloc() fails
Date:   Tue, 30 Aug 2022 22:10:09 +0800
Message-Id: <20220830141009.150075-1-chao@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Chao Yu <chao.yu@oppo.com>

In create_unique_id(), kmalloc(, GFP_KERNEL) can fail due to
out-of-memory, if it fails, return errno correctly rather than
triggering panic via BUG_ON();

kernel BUG at mm/slub.c:5893!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP

Call trace:
 sysfs_slab_add+0x258/0x260 mm/slub.c:5973
 __kmem_cache_create+0x60/0x118 mm/slub.c:4899
 create_cache mm/slab_common.c:229 [inline]
 kmem_cache_create_usercopy+0x19c/0x31c mm/slab_common.c:335
 kmem_cache_create+0x1c/0x28 mm/slab_common.c:390
 f2fs_kmem_cache_create fs/f2fs/f2fs.h:2766 [inline]
 f2fs_init_xattr_caches+0x78/0xb4 fs/f2fs/xattr.c:808
 f2fs_fill_super+0x1050/0x1e0c fs/f2fs/super.c:4149
 mount_bdev+0x1b8/0x210 fs/super.c:1400
 f2fs_mount+0x44/0x58 fs/f2fs/super.c:4512
 legacy_get_tree+0x30/0x74 fs/fs_context.c:610
 vfs_get_tree+0x40/0x140 fs/super.c:1530
 do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
 path_mount+0x358/0x914 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __arm64_sys_mount+0x2f8/0x408 fs/namespace.c:3568

Cc: <stable@kernel.org>
Reported-by: syzbot+81684812ea68216e08c5@syzkaller.appspotmail.com
Signed-off-by: Chao Yu <chao.yu@oppo.com>
---
 mm/slub.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 862dbd9af4f5..e6f3727b9ad2 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5890,7 +5890,8 @@ static char *create_unique_id(struct kmem_cache *s)
 	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
 	char *p = name;
 
-	BUG_ON(!name);
+	if (!name)
+		return ERR_PTR(-ENOMEM);
 
 	*p++ = ':';
 	/*
@@ -5948,6 +5949,8 @@ static int sysfs_slab_add(struct kmem_cache *s)
 		 * for the symlinks.
 		 */
 		name = create_unique_id(s);
+		if (IS_ERR(name))
+			return PTR_ERR(name);
 	}
 
 	s->kobj.kset = kset;
-- 
2.25.1