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[195.23.151.163]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e71b8011csm22383632f8f.31.2026.11.02.05.08.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Nov 2026 05:08:47 -0800 (PST) Sender: Julian Braha Message-ID: <1c3ec0f6-6c6b-4731-9c9f-809a047aa2c0@gmail.com> Date: Mon, 2 Nov 2026 13:08:46 +0000 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] kconfig: preprocess: fix UAF and SEGV on self-referencing variables To: Ruslan Semchenko , linux-kbuild@vger.kernel.org Cc: nathan@kernel.org, nsc@kernel.org, masahiroy@kernel.org, linux-kernel@vger.kernel.org References: <20261102090500.54575-1-uncleruc2075@gmail.com> Content-Language: en-US From: Julian Braha In-Reply-To: <20261102090500.54575-1-uncleruc2075@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Ruslan, On 11/2/26 09:05, Ruslan Semchenko wrote: > In variable_add(), when updating an existing simply expanded variable (:=), > v->value was freed before calling expand_string(value). If the value > referred to the variable itself (e.g. A := $(A)b), variable_expand() > accessed the already freed memory, causing a heap-use-after-free. > > Furthermore, for a new variable definition, an uninitialized variable > struct was inserted into variable_list before expanding value. If value > referred to the variable itself (e.g. B := $(B)x), variable_lookup() > found the incomplete variable and dereferenced uninitialized v->value, > causing a segmentation fault. > > Fix both issues by computing the new value before modifying the existing > variable or inserting a new one into variable_list. Thanks for your time & effort, but this was already caught some time ago: https://lore.kernel.org/all/20261008164504.3683811-1-lzsx618@gmail.com/ - Julian Braha