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Sat, 26 Sep 2026 08:24:16 -0700 (PDT) Received: from archlinux.lan ([136.34.156.120]) by smtp.gmail.com with ESMTPSA id 5614622812f47-4dbf6206942sm4653798b6e.9.2026.09.26.08.24.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 08:24:16 -0700 (PDT) From: Danish Khateeb To: Willy Tarreau , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Cc: Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Danish Khateeb Subject: [PATCH v2 0/2] tools/nolibc: check for overflow in malloc() Date: Sat, 26 Sep 2026 10:24:12 -0500 Message-ID: <20260926152414.251214-1-danishkhateeb03@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit malloc() does not check the addition of its header size for overflow, so malloc(SIZE_MAX), calloc(SIZE_MAX, 1) and realloc(ptr, SIZE_MAX) return a single page instead of NULL. As suggested by Thomas, patch 1 drops the rounding to 4096 bytes, and patch 2 adds the overflow check on top. Tested on x86_64 (GCC and clang), i386, and on arm, arm64 and sparc64 under qemu-user: - nolibc-test: no failures, with patch 1 alone and with the series. - A separate program: malloc(), calloc() and realloc() with sizes close to SIZE_MAX fail with ENOMEM, and free() still unmaps every page. Changes in v2: - Drop the rounding in a separate patch, instead of checking it for overflow (Thomas) - Drop the test patch (Thomas) - Link to v1: https://lore.kernel.org/r/20260926134332.58184-1-danishkhateeb03@gmail.com Danish Khateeb (2): tools/nolibc: stop rounding malloc() sizes up to 4096 bytes tools/nolibc: check for overflow in malloc() tools/include/nolibc/stdlib.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) base-commit: 0e1c44b472e1ec21efdad1df21b10e5c568b65b5 -- 2.55.0