From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 923AA402B9B for ; Mon, 18 May 2026 12:19:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779106786; cv=none; b=b5UGHERnVgnZBjwD8HcUNWYkgD+N0p6bCmnGSHutcy4771ls+vCQtz7PfA7QanXGW6zeBhJTZFsl0/uSrWIszpMvN0u953wP3eLnu4zQN4WiQCejf2avt35H9Lcr3hH8GDdqsByEAsbi4CoEOBs93U8sG7Uz5TOS3884c1Wra6U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779106786; c=relaxed/simple; bh=eLcdcZxrys2ehNx0yNlSxMilAqifYutDFaWElvOpaFo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=OxGE45FvHEJgxDoLPJRzbAo6PMOk5EY2hcMb0NJ5lLP3jV3xAl3ZOXaVVvv5ndIVwLLF3J6IjYYdH991qWaZIZshS5iStuAcwD9DavXTvdlIDZ7KF+rHGjw5B/fpbaicEuQGzbeHpamTKvV2Xw3yYRd+mzEAAQhy/fDL7qkbHA4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OPKk2ezY; arc=none smtp.client-ip=209.85.208.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OPKk2ezY" Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-67be871ed3fso5188789a12.1 for ; Mon, 18 May 2026 05:19:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779106783; x=1779711583; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=XVDi3PTBIMFWhncpu/t25cZzFWgAxfyBAa2471yPkMM=; b=OPKk2ezYSFGkS8dFH9tW4Xd6KdpAdlQmcpKRYtqssEwQPZd2ZC8nOlC0vl9gkeEP+2 avMmUFGnU/nuR08jdlTsho5YJ6ytzB6t0mSKtdWBscD/b8afGcKIJPGzKbj1fIl54bDC TbyG83AvgWSSJSOamOZZXc5AyVZtV1R5j5U/K9TK1URqJFkTpz33A8IoiG1XLqRvOVMm EvQaZuNr8u4l4HCvNqdicMhsqteF658Wo1VBMWqCmDLM1HYGuLF/cHgZlxHDDqfYlz/w SGYcJEK2y2B4e+I42nr/0mHB8ZN9TO4KogNwPxw1ZyJaBeE0EGc2KLt0Drhz1pIOHu9p Zhvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779106783; x=1779711583; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=XVDi3PTBIMFWhncpu/t25cZzFWgAxfyBAa2471yPkMM=; b=UzGpC9KTEKrGN1nuTDZgKfuAec3fJRrUZilVP0qHUoPrtdFAgNeYtgosxRRX00GzX2 e6wKQ33QjaQyRz0TciU1OLQ0d0oxJWzc7bxujB7wnQHOQ4J5m6tIuzCl6CNefNNIIirr ECu/QvkQqEED5SPx7pVB2xYpn0COcU4VQsmpWcKxl1vEES+mnrRduK1wa90y9f99jxoW vNV6LhfFjpq9OAvzj5uy9C3HRCkKEM7xj9oNf6b+wkSe5Im/d3b8M7BVjErJV+7VgIMV Sy9jYNWC52IEdMn/LK84Ij7kZnW2Oj6mc54ac8opxg9dRSXrgIKF4T/AW5Kgm+rENded 4CPg== X-Forwarded-Encrypted: i=1; AFNElJ82zwp8y+CU1tfMF6of419ET3SbLlnA/hS9XDjuihmJDBtKbjUJQiUUFre+jDF9XpWz9DxrWaU=@vger.kernel.org X-Gm-Message-State: AOJu0Yyn8i8AJtbcUS1lQlbUbi5ujCSNEmIRDrP+PUboHt1KVtq0lEzC BvA/qFzaxzZkDv1S/670TWqafGnoNLhRANEdrBagdOjQKqW9qGrnxM4c X-Gm-Gg: Acq92OFMWdKi7+e0Ev3OTZRZw7PX5StSPrZvmm77oxcOxlcxjfYxeHkioGVAQpmZ52K 2CWJhQxbjpZjWROAJxA8pnT10sr9koApG8dEjZWmypncGNKV1QZAu7v6oWBrccsEYCZtypWlM/E dPhvoPrwrTQS3XqZLs+tpAQWiNJx09gq7c/IY5mVfTJvWxd6M2oBPWFlXZn4sdTlHPM991jkUfZ QNS47p0VqtDT8kqKbCjadVPpwHZdoZnOkxAHHrm1rc8kn1pJ0huuxhyIC7esQ1xMCzzT/9rKSQv zfD+RLrngVX1WPsNubpUkxlWcoo2nI48Uw11EsR0UBEl2M++X/DtStbuxm4TSTqfCjO2cqeYX8K RswgOKFSqBzGPjKmWTusSh7B3A2utjsi1C21jhrYB/CptJNqVI54CCsoTvmTsrfBd04LoMPj8v/ xM57gDy2fK9Iejio+I5ldt7ZlVPae+/g== X-Received: by 2002:a17:907:3d11:b0:bb9:c23:573d with SMTP id a640c23a62f3a-bd517964d61mr715072566b.31.1779106782560; Mon, 18 May 2026 05:19:42 -0700 (PDT) Received: from nixbug.lan ([146.120.47.171]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-bd4f4bcf7f3sm551533266b.2.2026.05.18.05.19.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2026 05:19:42 -0700 (PDT) From: Andrii Kuchmenko To: linux-modules@vger.kernel.org Cc: chleroy@kernel.org, mcgrof@kernel.org, dmitry.torokhov@gmail.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Andrii Kuchmenko Subject: [PATCH v2] module: decompress: check return value of module_extend_max_pages() Date: Mon, 18 May 2026 15:18:58 +0300 Message-ID: <20260518121858.3071-1-capyenglishlite@gmail.com> X-Mailer: git-send-email 2.51.2 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit module_extend_max_pages() calls kvrealloc() internally and returns -ENOMEM on allocation failure. The return value is never checked. The decompression loop then continues calling module_get_next_page(), which writes struct page pointers into info->pages[]. When used_pages reaches the stale max_pages value (not updated due to the failed extend), a subsequent write to info->pages[used_pages++] goes out of bounds into adjacent heap memory. Adjacent slab objects in the same kmalloc cache (pipe_buffer, seq_operations, cred) can be corrupted, potentially leading to local privilege escalation on kernels without SLAB_VIRTUAL mitigation. The call order in finit_module() is: module_decompress() <- vulnerable, runs FIRST load_module() module_sig_check() <- signature check, runs SECOND Decompression happens before signature verification. A crafted compressed module submitted via finit_module(MODULE_INIT_COMPRESSED_FILE) reaches this code path before any signature gate is applied. On kernels with module.sig_enforce=0 (default without SecureBoot) or with unprivileged user namespaces (Ubuntu, Debian default), this is reachable without CAP_SYS_MODULE. Confirmed present in mainline (tested on v6.14-rc3). Fix: add the missing error check after module_extend_max_pages() and return immediately on failure. This matches the pattern used by every other kvrealloc() caller in the module loading path. Fixes: 169a58ad824d ("module: add in-kernel support for decompressing") Cc: Dmitry Torokhov Cc: Luis Chamberlain Cc: stable@vger.kernel.org Signed-off-by: Andrii Kuchmenko --- kernel/module/decompress.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c --- a/kernel/module/decompress.c +++ b/kernel/module/decompress.c @@ -XXX,9 +XXX,12 @@ int module_decompress(struct load_info *info, const void *buf, size_t size) { unsigned int n_pages; int error; ssize_t data_size; n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2; error = module_extend_max_pages(info, n_pages); + if (error) + return error; data_size = MODULE_DECOMPRESS_FN(info, buf, size); if (data_size < 0) { error = data_size; -- 2.39.0