Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails

[Hyeonggon Yoo]

On Tue, Aug 30, 2022 at 10:10:09PM +0800, Chao Yu wrote:
> From: Chao Yu <chao.yu@xxxxxxxx>
> 
> 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@xxxxxxxxxx>
> Reported-by: syzbot+81684812ea68216e08c5@xxxxxxxxxxxxxxxxxxxxxxxxx

Fixes: 81819f0fc8285 ("SLUB core")

> Signed-off-by: Chao Yu <chao.yu@xxxxxxxx>
> ---
>  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
> 
> 

Looks good to me.

Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>

Thanks!

-- 
Thanks,
Hyeonggon