Re: [PATCH bpf-next 08/16] bpf: Handle bpf_dynptr_user in bpf syscall when it is used as input

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Hou,

kernel test robot noticed the following build warnings:

url:    https://github.com/intel-lab-lkp/linux/commits/Hou-Tao/bpf-Introduce-map-flag-BPF_F_DYNPTR_IN_KEY/20241008-171136
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20241008091501.8302-9-houtao%40huaweicloud.com
patch subject: [PATCH bpf-next 08/16] bpf: Handle bpf_dynptr_user in bpf syscall when it is used as input
config: x86_64-randconfig-161-20241011 (https://download.01.org/0day-ci/archive/20241012/202410120530.zUoa1scp-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202410120530.zUoa1scp-lkp@intel.com/

smatch warnings:
kernel/bpf/syscall.c:1557 bpf_copy_from_dynptr_ukey() warn: 'key' is an error pointer or valid

vim +/key +1557 kernel/bpf/syscall.c

e1883aa78ac1fe9 Hou Tao            2024-10-08  1543  static void *bpf_copy_from_dynptr_ukey(const struct bpf_map *map, bpfptr_t ukey)
e1883aa78ac1fe9 Hou Tao            2024-10-08  1544  {
e1883aa78ac1fe9 Hou Tao            2024-10-08  1545  	const struct btf_record *record;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1546  	const struct btf_field *field;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1547  	struct bpf_dynptr_user *uptr;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1548  	struct bpf_dynptr_kern *kptr;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1549  	void *key, *new_key, *kdata;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1550  	unsigned int key_size, size;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1551  	bpfptr_t udata;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1552  	unsigned int i;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1553  	int err;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1554  
e1883aa78ac1fe9 Hou Tao            2024-10-08  1555  	key_size = map->key_size;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1556  	key = kvmemdup_bpfptr(ukey, key_size);
e1883aa78ac1fe9 Hou Tao            2024-10-08 @1557  	if (!key)

This should be if (IS_ERR(key))

e1883aa78ac1fe9 Hou Tao            2024-10-08  1558  		return ERR_PTR(-ENOMEM);
e1883aa78ac1fe9 Hou Tao            2024-10-08  1559  
e1883aa78ac1fe9 Hou Tao            2024-10-08  1560  	size = key_size;
e1883aa78ac1fe9 Hou Tao            2024-10-08  1561  	record = map->key_record;

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