From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) (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 3CE642F360A for ; Tue, 26 May 2026 02:18:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779761914; cv=none; b=GVgcldfRfwUG/VFdil4ilyguDwq0v1UI7t5vqlIz4s5TgyqfVUQLtYJN2oQcR9EVj5gsf0LTEGs02eaPnkB4A+uy7UmyJ7LWfD4tRGVGeL5FhIWSdj+6T3I7HilQYVej89ytfJgsU0TPj4HGMmd6m1zDiAeniEiWGpEC2nAJWRs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779761914; c=relaxed/simple; bh=ugOr6h9qKSCXcCA2J2qmDK1c4p4CH4hY+NbjnHqvdDU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=g1xOro1c7Fe5+J3DpDMutmhhPRsBZi0XkaCsAkXXbYBwtk1SfiIPxjWRi/mE+z3EKh4PVJswlM/1axVYtbGF0AseddN3rkRIHUXF4gXYigsERRKk5eRyLhE941MJbI2SA45twU7x307qS9fciANcOZWpIXtBq2aUP0KgeXtn4Xg= 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=RJyEA+Fu; arc=none smtp.client-ip=209.85.214.182 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="RJyEA+Fu" Received: by mail-pl1-f182.google.com with SMTP id d9443c01a7336-2be75f658f3so49064695ad.1 for ; Mon, 25 May 2026 19:18:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779761912; x=1780366712; 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=xaHr4apjjXax6lzaZFsAAU5p0KUItY7eRXmilQ6CXh4=; b=RJyEA+FuwvFylfdlVWo6rFpJ71bFbR3ViQf4j6KV69Sg6pCf+oUtwihhm8XTdJP/5t apeT0x2wQxiuIkMLZLQSfOARMNqVHpFKmiFZjyPSX9z2zoOSeMMV43eQUkPBBNCdePLN N0NjVzJrQ2zPsw+Jb9vr5UV+iBJj7WZpa4KddUqPbNYOFQS8erAj5+j4Uw8iYVLjBH5M R/lI/J4oC9tK5F3YWUwJ93kGbpdmeHzDOtbuBYq1fYNEkOm2SQG9+9RcXL6TxpLrkBeS xr+iUimqIUxYNT1XvKLf3thnkLZmNH0ZQ+t/q/ksqoBc1LTkvSC4xAMzyYDiJvGF/A1Z 0NKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779761912; x=1780366712; 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=xaHr4apjjXax6lzaZFsAAU5p0KUItY7eRXmilQ6CXh4=; b=N7am03+Ldpk/DKpOLdoCAhrmJxlL21E2n4mq0dupN+0QXc8zCHZhCahujblxk+Vflb CwEMM5B26IvTm/J69ZxdHjZdx6qL+xW1CSVW/ZaBGEv9H9RmB/A7rDdqUAHmnPeC5O7M 0GKFv+t+DLofF9bZDRIvXXK4HCy18pvjFTWHaJvgGVcKi5WuK987xeTBn57UU2zcU2oB yxyEOIaqFkDpYNLK/iBloeHzBRE/mb4oCe0w38nIA4ecLyBkb0lsvwYnoi1z+v48QGSv sEo4OPj6iHKblPLtfKi8sSC272z8IIENQAukKt+DFLpCNnP7AF2hVmJlmkHWs35k1MbX eDHQ== X-Forwarded-Encrypted: i=1; AFNElJ+2cput1GSWmZg+TGiIVPeYQYd2jVPz/g0yNjH2ltXvwT/BkXcAi4N3blohkEcgKRqHjOdleQ65EUU4g2A=@vger.kernel.org X-Gm-Message-State: AOJu0YygL66pTHQq22GzM4xY43C130CGjbp4ijL94qq829X5X9km5ysP E48XHRxgXlftSTdwfD+4mlNK1kEr913L4FbzV392FAi9q9kxySqLEaZVDSEAKDsc X-Gm-Gg: Acq92OHRMuDKRT23Ctv3czNukURSushboS7jMCjK4aUzRtkYz68Wsm62osciqFYBf3H pYTpa/lb0+xmQZQeK6kdVE+XcF9Zdh66kdC1BPO5t9ShJAzW8pICbDlVHMfs5IW34OySUmF4TdU mHhaSjDEVoKbJ5ztHd2nHjiFnairDRBIQsITt4XrXPu4MaMBb/ubQM6i2sKYsCANEqNM4L81xR6 N+osogVj8TDdBYq55GAbPCjeLCU+mpNgFB8vd9f42AoqB0dh8Vg7anZI0K8EvRpUxMoR7e2FQSk bP/AKYwtl6cmzQfOfMxxlKBkkPziW5QplEIccxIWYjOR8tKJp64hb0i+QWq5TPlQjgw3394w9R0 HuDhuvPY/sKYpKmhEbDDMUpLU3vvEpwBRC/WbrIvT58INIsEtWzZOenD3Bx6LoktoIzqcgQoAHo 1TAevKsLcQwOQCDP4ecEUMvLfzj1wpd7NfhWVqbec7c9gIcr7AzGZIPZ9yfoXcywm6yCqzHZHTZ U5016lBttYiCnrvHdITwaM5tgUNqe/wtkKVi3NBroykFE4CisRVBSkI3Sf0TFCoUf8xnGDq0pzj Sfi20SYJen446Ho= X-Received: by 2002:a17:903:196b:b0:2ba:6ebe:4897 with SMTP id d9443c01a7336-2beb069a893mr171232725ad.3.1779761912481; Mon, 25 May 2026 19:18:32 -0700 (PDT) Received: from codespaces-78f0a7.mimvmn1ww3huhhjmzljqefhnig.rx.internal.cloudapp.net ([4.240.39.194]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2beb591d07fsm112242735ad.82.2026.05.25.19.18.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 19:18:32 -0700 (PDT) From: Muhammad Bilal To: linux-bluetooth@vger.kernel.org Cc: marcel@holtmann.org, luiz.dentz@gmail.com, gregkh@linuxfoundation.org, johan.hedberg@intel.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v1 1/1] Bluetooth: L2CAP: fix heap over-read in l2cap_get_conf_opt Date: Tue, 26 May 2026 02:17:47 +0000 Message-ID: <20260526021747.31634-1-meatuni001@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit l2cap_get_conf_opt() reads opt->val via a switch on opt->len (1, 2, or 4 bytes). opt->len is a remote-controlled u8. All three callers loop on (len >= L2CAP_CONF_OPT_SIZE), so the loop body executes with as few as 2 bytes remaining. A packet ending with opt->len=4 and only 2 bytes left causes get_unaligned_le32(opt->val) to read 4 bytes past the buffer before the caller can act on the return value. Commit 7c9cbd0b5e38 ("Bluetooth: Verify that l2cap_get_conf_opt provides large enough buffer") added a post-call len < 0 guard in each caller, but the over-read fires inside l2cap_get_conf_opt() before that guard is reached. Add a buflen parameter and validate L2CAP_CONF_OPT_SIZE + opt->len <= buflen before any access to opt->val. Return -EINVAL on violation. Update all three callers to capture the return value and break on negative. With the bounds check ensuring the option fits within the remaining buffer, the post-call len < 0 check is no longer needed and is removed. Fixes: 7c9cbd0b5e38 ("Bluetooth: Verify that l2cap_get_conf_opt provides large enough buffer") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Bilal --- net/bluetooth/l2cap_core.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index fdccd62ccca8..6052ffb280ac 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -3051,12 +3051,23 @@ static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn, u8 code, } static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen, - unsigned long *val) + unsigned long *val, size_t buflen) { struct l2cap_conf_opt *opt = *ptr; int len; + /* Guard opt->len dereference: reject if the 2-byte option header + * itself does not fit in the remaining buffer. + */ + if (buflen < L2CAP_CONF_OPT_SIZE) + return -EINVAL; + len = L2CAP_CONF_OPT_SIZE + opt->len; + + /* Reject options whose payload extends past the remaining buffer. */ + if ((size_t)len > buflen) + return -EINVAL; + *ptr += len; *type = opt->type; @@ -3437,9 +3448,11 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data BT_DBG("chan %p", chan); while (len >= L2CAP_CONF_OPT_SIZE) { - len -= l2cap_get_conf_opt(&req, &type, &olen, &val); - if (len < 0) + int optlen = l2cap_get_conf_opt(&req, &type, &olen, &val, len); + + if (optlen < 0) break; + len -= optlen; hint = type & L2CAP_CONF_HINT; type &= L2CAP_CONF_MASK; @@ -3675,9 +3688,11 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, BT_DBG("chan %p, rsp %p, len %d, req %p", chan, rsp, len, data); while (len >= L2CAP_CONF_OPT_SIZE) { - len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val); - if (len < 0) + int optlen = l2cap_get_conf_opt(&rsp, &type, &olen, &val, len); + + if (optlen < 0) break; + len -= optlen; switch (type) { case L2CAP_CONF_MTU: @@ -3946,9 +3961,11 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len) return; while (len >= L2CAP_CONF_OPT_SIZE) { - len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val); - if (len < 0) + int optlen = l2cap_get_conf_opt(&rsp, &type, &olen, &val, len); + + if (optlen < 0) break; + len -= optlen; switch (type) { case L2CAP_CONF_RFC: -- 2.53.0