Re: [PATCH v2] mm/slub: fix to return errno if kmalloc() fails

Vlastimil Babka (SUSE)
2022-09-08T21:35:04Z

On 8/31/22 16:54, Chao Yu wrote:
> 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>
> Fixes: 81819f0fc8285 ("SLUB core")
> Reported-by: syzbot+81684812ea68216e08c5@syzkaller.appspotmail.com
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Signed-off-by: Chao Yu <chao.yu@oppo.com>

Added to slab.git for-6.0/fixes

> ---
> v2:
> - add more rvb tags and fixes line
> 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;