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Wed, 19 Nov 2025 03:13:23 -0800 (PST) Received: from mail.gmail.com ([2a04:ee41:4:b2de:1ac0:4dff:fe0f:3782]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42b53f1fd50sm37634471f8f.38.2025.11.19.03.13.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Nov 2025 03:13:22 -0800 (PST) Date: Wed, 19 Nov 2025 11:20:14 +0000 From: Anton Protopopov To: Dan Carpenter Cc: bpf@vger.kernel.org Subject: Re: [bug report] bpf, x86: add support for indirect jumps Message-ID: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 25/11/19 11:35AM, Dan Carpenter wrote: > Hello Anton Protopopov, > > Commit 493d9e0d6083 ("bpf, x86: add support for indirect jumps") from > Nov 5, 2025 (linux-next), leads to the following Smatch static > checker warning: > > kernel/bpf/verifier.c:17907 copy_insn_array() > error: 'value' dereferencing possible ERR_PTR() > > kernel/bpf/verifier.c > 17898 static int copy_insn_array(struct bpf_map *map, u32 start, u32 end, u32 *items) > 17899 { > 17900 struct bpf_insn_array_value *value; > 17901 u32 i; > 17902 > 17903 for (i = start; i <= end; i++) { > 17904 value = map->ops->map_lookup_elem(map, &i); > 17905 if (!value) > 17906 return -EINVAL; > --> 17907 items[i - start] = value->xlated_off; > > ->map_lookup_elem() returns error pointers on error and it returns NULL > (I guess if there isn't an error but the element is not found). I didn't check the value here, because in this case map_lookup_elem() always returns a correct value or NULL (= index is outside of boundaries). >From BPF point of view, map_lookup_elem must return valid pointer, or null (see the bpf_map_lookup_elem_proto in kernel/bpf/helpers.c). But some lookup functions might be called from kernel (as in this case) or from userspace via the syscall. So I'll send a fix to add a check here and make the static checker happy. > 17908 } > 17909 return 0; > 17910 } > > regards, > dan carpenter