From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793907763; b=1ikAKhE2JmufCAsP09N4QhgA/xPKzEYrcIyLOBLuNiTp/WfvROBGmoeSJ06gPM88M2In 6aoJlfr5rUKsiv4XJwtaKQlQwHs2alUxTmal2YNBa9ANtyKIDWl7589WeZaOk6acBnFGM I2KH5FgJz6wHVwFmTpGsyHefwQRjc2QCZAsDa78E2rMM5u74XPs17SresPdzme1zYnGPP ZKY4i1naLHQOgHt9f4I3viq8iMp5NKe7MTVCjE8hhI7oEA1W2heb1tDDgqOhQBcKb6a/c lGdKQbGGAJKmiYJ6DVgZuGoD9Vga6mTbn/69vS79ZbmZeHj0vdJs21v8MVbyiBWNKoQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793907763; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=PWm6vf/ymT7/ctxOoAv3DVxfgR9bNkbX3NAccpGDFDE=; b=FzV6i9ZHcEGXjHS1tNYlajJe6YF9hTZSz4e0XnxPphHnmL/olc7fBDa/hvAKByl3IbyZ 9gieaPY9O/nAZpCj5OoZQSTaTWNhf2ERqx1wOYFJPsw5HGx2/MDlo7K/hk7KpuhFdhe5r OOLKnQJEFYziUfuACzJrJC0eAAlmySZylKCSCq27muuXO1zIlWvgfmPtzdOiazd3dc4yO sQ64E+datr5c0sL4+vBW/rIjHHg0ajVpb4+UBOkH+9BGCr97o6PD6hjspax8duvxFR2sJ G75k+YCO8aFOG/Es5xTM5PkiysAfMLHpa1ZIk0qnu6OjWRnBAHEtLcVs6aZ7UTfvGfA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="bPZsa99/"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 692A9607857B for ; Thu, 5 Nov 2026 19:42:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bPZsa99/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id B101D1F008A1; Thu, 5 Nov 2026 19:42:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793907763; bh=PWm6vf/ymT7/ctxOoAv3DVxfgR9bNkbX3NAccpGDFDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bPZsa99/1EFfiljFgmJvie4IoVlZUOuFBkjF6Jk4zCmDYRSBiM41Z35bEfEez/uS4 GUJPeDKvmszvXR9/K/Rz47cXUlaEwyBRjoX6fvpFj5Glza8tYabzRFqHOTbe4DCvZM 9Mxl6IohCot5qPv2EjGgQHBPObb4EvRr/3yuGjuIlBF2oaAtKNOd8yNCzZLr7XEFLu w+01XCgPNMJvdxx1wThiLuj0XgYH8hpZLovcuLXpI3rwDrbxZtEz98EVlp6uaY6RHL 5XnsE5yEivATqAdMcAFMFSDnpI4neVL1m9gjMBt20AJN1U9V8K1UL7pOpk6LhoGIZt QT/vximpSxhdw== From: Sasha Levin To: stable@vger.kernel.org Cc: Ratnaker Gautam , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.15.y] smb: client: bound POSIX lock data area by response length Date: Thu, 5 Nov 2026 14:42:41 -0500 Message-ID: <20261105193924.2633468-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110407-purchase-culminate-fc4e@gregkh> References: <2026110407-purchase-culminate-fc4e@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ratnaker Gautam [ Upstream commit 8fc9af68c57156ff64769f30e831553cd03b3000 ] CIFSSMBPosixLock() receives a TRANS2 response whose server-provided DataOffset and DataCount are not required by validate_t2() to describe an interval inside the response. A server can therefore make the client read a cifs_posix_lock beyond the response buffer and return those kernel bytes through F_GETLK. Use smbCalcSize() to obtain the full response length after any multipart TRANS2 reassembly, then reject data areas that extend past it before dereferencing them. Fixes: fc94cdb94462 ("[CIFS] Fix new POSIX Locking for setting lock_type correctly on unlock") Reported-by: Ratnaker Gautam Cc: stable@vger.kernel.org Signed-off-by: Ratnaker Gautam Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara [ sashal: Subtracted the four-byte transport prefix from smbCalcSize() to match protocol-relative offsets. ] Signed-off-by: Sasha Levin --- fs/cifs/cifssmb.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index 11a400663b9f2..c792de4c706c1 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -2481,6 +2481,7 @@ CIFSSMBPosixLock(const unsigned int xid, struct cifs_tcon *tcon, cifs_dbg(FYI, "Send error in Posix Lock = %d\n", rc); } else if (pLockData) { /* lock structure can be returned on get */ + unsigned int rsp_len; __u16 data_offset; __u16 data_count; rc = validate_t2((struct smb_t2_rsp *)pSMBr); @@ -2491,10 +2492,16 @@ CIFSSMBPosixLock(const unsigned int xid, struct cifs_tcon *tcon, } data_offset = le16_to_cpu(pSMBr->t2.DataOffset); data_count = le16_to_cpu(pSMBr->t2.DataCount); + rsp_len = smbCalcSize(&pSMBr->hdr) - 4; if (data_count < sizeof(struct cifs_posix_lock)) { rc = -EIO; goto plk_err_exit; } + if (data_offset > rsp_len || + data_count > rsp_len - data_offset) { + rc = -EIO; + goto plk_err_exit; + } parm_data = (struct cifs_posix_lock *) ((char *)&pSMBr->hdr.Protocol + data_offset); if (parm_data->lock_type == cpu_to_le16(CIFS_UNLCK)) -- 2.53.0