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([2a0a:ef40:7a5:4701:8cee:45ed:2bd5:e17c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b79c3c4beasm46360397f8f.30.2025.08.13.06.19.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Aug 2025 06:19:16 -0700 (PDT) Message-ID: <5303c45e-d95b-4bc8-9cd1-bf4efe6bfbae@gmail.com> Date: Wed, 13 Aug 2025 14:19:14 +0100 Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: phillip.wood@dunelm.org.uk Subject: Re: Potential Null Pointer Dereference detected by static analysis tool To: Cheng , git@vger.kernel.org References: Content-Language: en-US From: Phillip Wood In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Cheng On 13/08/2025 01:23, Cheng wrote: > > > line 326 in builtin/describe.cdescribe.c, which is located in the function describe_commit. In the following code, cmit could be NULL passed to the call, which then causes a NULL dereference. Seems should be replaced lookup_commit_reference with lookup_commit_or_die. > > > ```cpp > cmit = lookup_commit_reference(the_repository, oid); > n = find_commit_name(&cmit->object.oid); > ``` > > > > The NULL value seems to come from function lookup_commit_reference_gently where: > > - 1. call to deref_tag may return NULL. > > - 2. call to object_as_type may return NULL. > > > In this repository, other calls  lookup_commit_reference are followed by a null check. So this seems to lead to NULL dereference. Can I confirm with you whether this is a true positive bug report? I had a quick look at the callers of describe_commit() and they all seem to use an oid that they get from looking up a commit so I'm not sure under what circumstances this call to lookup_commit_reference() can fail. Thanks Phillip