[PATCH v2 08/13] bpf: Implement signature verification for BPF programs

[Dan Carpenter]

Hi KP,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/KP-Singh/bpf-Update-the-bpf_prog_calc_tag-to-use-SHA256/20250722-052316
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20250721211958.1881379-9-kpsingh%40kernel.org
patch subject: [PATCH v2 08/13] bpf: Implement signature verification for BPF programs
config: m68k-randconfig-r073-20250723 (https://download.01.org/0day-ci/archive/20250723/202507231202.8rYZJ8D1-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 14.3.0

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 at intel.com>
| Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
| Closes: https://lore.kernel.org/r/202507231202.8rYZJ8D1-lkp@intel.com/

smatch warnings:
kernel/bpf/syscall.c:2797 bpf_prog_verify_signature() warn: 'sig' is an error pointer or valid

vim +/sig +2797 kernel/bpf/syscall.c

c83b0ba795b625 KP Singh           2025-07-21  2782  static noinline int bpf_prog_verify_signature(struct bpf_prog *prog,
c83b0ba795b625 KP Singh           2025-07-21  2783  					      union bpf_attr *attr,
c83b0ba795b625 KP Singh           2025-07-21  2784  					      bool is_kernel)
c83b0ba795b625 KP Singh           2025-07-21  2785  {
c83b0ba795b625 KP Singh           2025-07-21  2786  	bpfptr_t usig = make_bpfptr(attr->signature, is_kernel);
c83b0ba795b625 KP Singh           2025-07-21  2787  	struct bpf_dynptr_kern sig_ptr, insns_ptr;
c83b0ba795b625 KP Singh           2025-07-21  2788  	struct bpf_key *key = NULL;
c83b0ba795b625 KP Singh           2025-07-21  2789  	void *sig;
c83b0ba795b625 KP Singh           2025-07-21  2790  	int err = 0;
c83b0ba795b625 KP Singh           2025-07-21  2791  
c83b0ba795b625 KP Singh           2025-07-21  2792  	key = bpf_lookup_user_key(attr->keyring_id, 0);
c83b0ba795b625 KP Singh           2025-07-21  2793  	if (!key)
c83b0ba795b625 KP Singh           2025-07-21  2794  		return -ENOKEY;
c83b0ba795b625 KP Singh           2025-07-21  2795  
c83b0ba795b625 KP Singh           2025-07-21  2796  	sig = kvmemdup_bpfptr(usig, attr->signature_size);
c83b0ba795b625 KP Singh           2025-07-21 @2797  	if (!sig) {

This should be an if (!IS_ERR(sig)) { check.

c83b0ba795b625 KP Singh           2025-07-21  2798  		bpf_key_put(key);
c83b0ba795b625 KP Singh           2025-07-21  2799  		return -ENOMEM;
c83b0ba795b625 KP Singh           2025-07-21  2800  	}
c83b0ba795b625 KP Singh           2025-07-21  2801  
c83b0ba795b625 KP Singh           2025-07-21  2802  	bpf_dynptr_init(&sig_ptr, sig, BPF_DYNPTR_TYPE_LOCAL, 0,
c83b0ba795b625 KP Singh           2025-07-21  2803  			attr->signature_size);

-- 
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https://github.com/intel/lkp-tests/wiki