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 1A53B39F18A; Sat, 12 Sep 2026 19:06:11 +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=1789239972; cv=none; b=Ykq0pT0nlcxI4lJwHl106Wo3xjxuI5qCq2eLGn5ViY3vyW8Ji7SmOXNNY9hArcrAJBH40D5GQ5mIXQn2IgtYjLqAUyBO7dkD8xgURN4pP2KZ+nlQ56seCAzkJy+nqM8g6gAlOpZiWjINZD0uqJUYGgEG+P8hv///4AnLo96D7bs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789239972; c=relaxed/simple; bh=ug9xpDW5eR6TpaATDLZ8j/ZVg05E2OzVXx4SIjSS7U8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XhJhvwdew4P6+Hd+5iFCohJzGcieQK24oca9wD+n6wH/y60gZnqAGE/auszNPA7VQgM/n30umnVDxNskBZ8kM+h24ODtnQmt2UL9TWkAPZKI7tM7pH2DiIFRDOd/ikQn7rSuZ/o6TwFgSOLl9Z0UBmf7aB0DUg8Tt0U1XxOk4t4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HsOsY2nq; 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="HsOsY2nq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC3BA1F000FF; Sat, 12 Sep 2026 19:06:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789239971; bh=xx2JDT0SZxNPxKuf2o/NkqgE74SZkks4E1iBxPJqiKM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HsOsY2nqxcHdlLOfzQrccsygnmyvvhA3cJVjefNGpkKJ7S/sQiG/bR4Qn8625hErn p7v7m1Mcau2DKt3KfZqWj8mQ2oTgM2wj/5MvQmCIEGklOEI4u7+T8wo4Rt182qFcFe d6zLb8e88Xu9cFHkSgSFa6G5IItklzNLnKm7gGaM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Breno Leitao , Simon Horman , David Heidelberg , Sasha Levin Subject: [PATCH 5.15 774/935] nfc: llcp: read llcp_sock->local under the socket lock in getsockopt Date: Sat, 12 Sep 2026 09:03:24 +0200 Message-ID: <20260912065544.581781047@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Breno Leitao [ Upstream commit 36812527052c5bfb1ec6c1e292d67a5bf76b750f ] nfc_llcp_getsockopt() read llcp_sock->local before lock_sock(sk) and then dereferenced the cached pointer inside the locked region. llcp_sock_bind() assigns and clears llcp_sock->local under the same socket lock, dropping the last reference on its error path. A getsockopt() racing an in-flight bind() can observe the pointer, block on lock_sock(), and then dereference a freed nfc_llcp_local once bind() has unwound. Move the llcp_sock->local read and the NULL check inside the lock_sock(sk) region so bind() cannot mutate or free the pointer between the load and the use. Fixes: 26fd76cab2e6 ("NFC: llcp: Implement socket options") Signed-off-by: Breno Leitao Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260521-fix_llc-v2-2-ab44cc09179c@debian.org Signed-off-by: David Heidelberg Signed-off-by: Sasha Levin --- net/nfc/llcp_sock.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index 0ba5ffe0ce6d1..85767c13543b5 100644 --- a/net/nfc/llcp_sock.c +++ b/net/nfc/llcp_sock.c @@ -320,14 +320,16 @@ static int nfc_llcp_getsockopt(struct socket *sock, int level, int optname, if (len < sizeof(u32)) return -EINVAL; - local = llcp_sock->local; - if (!local) - return -ENODEV; - len = min_t(u32, len, sizeof(u32)); lock_sock(sk); + local = llcp_sock->local; + if (!local) { + release_sock(sk); + return -ENODEV; + } + switch (optname) { case NFC_LLCP_RW: rw = llcp_sock->rw > LLCP_MAX_RW ? local->rw : llcp_sock->rw; -- 2.53.0