From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D6EA582B98 for ; Fri, 11 Sep 2026 20:01:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156899; cv=none; b=oN9Mc1NoMOISeb3oZI0/KGtFo4+Fp5vWrOECvFdiJsFs9kO3Y0d6Qr2mXf+rttXeb0G0IYsqoRmpQsTe1KDqaulS09Yj3cIMn9BZhM0FTbebRHsh5T5rosJ7KdI0vHUf8PRFpKqizij4bu6iWCl3jzTOwbBwCdCom1pXP7cNlgY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156899; c=relaxed/simple; bh=ytCmTpbSE6nQn6fpsjLpGLoPSddZEE0eSpdHhRjEdmE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dSMUGwmp7JTL5AVraF9txQeXRjrLgMqVhdsiE4oVuWdPl25OoP8hvDrf0+1Xdy2D95slTuVqadfHVYpBrrcfI6FMYGNdLyZT1FZA6xabK5I5oJSFxqvKljKz4XJVbDjihDEUVpv7PXlGXwu15U4XiRNmp9OQtXL9BGXBCDUMPhw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=APGhdZKU; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="APGhdZKU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A02F1F0089F; Fri, 11 Sep 2026 20:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156895; bh=EiWfZB2emGsBouecbf2oB4JIoxrKcAcAH8fz+f5383s=; h=From:To:Cc:Subject:Date:Reply-To; b=APGhdZKUITjXSsLmCqA0eCyi3CEc5tGLunXJCw1Z7Oy4HVx+LtneEkK9fOuZFP84x WzVBq2R36r0qGFCWj0r/3kfkNBFuxFtdr+ccyutYppQ7w6mA8Tan1tnq4XpBImHwzJ 99fr7XUOfGPi5wTyotaxOTJjKBBkuBgqO3xUnmdU= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89633: smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() Date: Fri, 11 Sep 2026 21:45:22 +0200 Message-ID: <2026091140-CVE-2026-89633-e1e3@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3122; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=RG81gOzCTwh8446l6T1OD72eUp3XNFZ+E3llcVP1kBo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIksup58O3tr3TUQx8AZnrq5Yxjq+ECe38tliJ66oS 21l5yrtiGVhEGRikBVTZPmyjefo/opDil6Gtqdh5rAygQxh4OIUgIkE7mWYH/bFyjqE/33RXInV 3U1f195X35B3nmGeNsOsW5vuCByR2xDLJ/ElUfpB/vPlAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() coalesce_t2() computes data pointers directly from server-supplied DataOffset fields with no validation against buffer bounds: data_area_of_tgt = (char *)&pSMBt->hdr.Protocol + get_unaligned_le16(&pSMBt->t2_rsp.DataOffset); data_area_of_src = (char *)&pSMBs->hdr.Protocol + get_unaligned_le16(&pSMBs->t2_rsp.DataOffset); data_area_of_tgt += total_in_tgt; ... memcpy(data_area_of_tgt, data_area_of_src, total_in_src); A small DataOffset can push a pointer below the actual byte area, overwriting header fields; a large one can push it past the buffer end, causing out-of-bounds heap reads (source) or writes (target). The BCC overflow guard does not prevent this: BCC reflects how much data is present, while DataOffset controls where in the buffer it starts. The "validate target area" comment present since the function was first written in 2005 was a placeholder that was never implemented. Add lower- and upper-bound checks for both data pointers before the memcpy, and before any target header fields are modified. The Linux kernel CVE team has assigned CVE-2026-89633 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.12 with commit e4eb295d38b57f4d4b956942a48887eb252d97c6 and fixed in 6.18.51 with commit 672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e Issue introduced in 2.6.12 with commit e4eb295d38b57f4d4b956942a48887eb252d97c6 and fixed in 7.2.4 with commit 033bc80019f07d158630df4e69b19a49010f54f1 Issue introduced in 2.6.12 with commit e4eb295d38b57f4d4b956942a48887eb252d97c6 and fixed in 7.3-rc1 with commit 6343c1da561962688f203362d80d6a3bfa39fa1b Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-89633 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: fs/smb/client/smb1transport.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1 https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b