From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 5B7423DA5BD; Thu, 21 May 2026 14:33:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779374028; cv=none; b=DeIkU3Aiio/I5OB4uLpfwBLARGxdyGXHWshieGDUQ0JcEyGIzOoR3hv5LiCgSWt6hhMUmCMsyiqwdzlv/wA5xK3PmqSdFhkQAQYZvtzZVJstng80dGUT9pgwheEw1n1sDgcnAQhUMCNKb4Ah0zd193mOC9V246YuPqZZAfeNkYk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779374028; c=relaxed/simple; bh=vUVzwioy7eyITUTnDSAg54tCJT7WpcF3kD1sfAlb9Xg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sSES84gI3HzIm5L70/WYPp100UuV/gHZ2am2b82VrEviRQ6eqPn5DFgkZ2WJ2osWBV1MvXneNXyIbCAuFsEBL7Z8ddxeUy44C5x++Ly5O9hFQmB/CdYiaFz7GGupLXniI2xqgPbfZJqCvcJXxL95lDA17Jm9bMzU8xOFt/cL2zQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=a0dVKJ+m; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="a0dVKJ+m" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:Cc:To:In-Reply-To:References: Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description; bh=1CytHvX5Z9CQODF2r8Uldp/4soH5aVdVyJhj02K+WN4=; b=a0dVKJ+mpjGCdpOj1QsIJMvtlR xVM9K3vUwb5P3qDxarN0I7G1jum0faoZGGaOY3UiPAxwmYKQY0bh33eot2lKD0GVZQxZU5g9X48B2 Z4aqiiLpwUlN8JcZ7w8fwL26VDi8VAyBtxovhpSm6p2JNVAXBW9QPh/gt9oHeIDm9piBuggky7N0R YycSBecv44DYTYFIh/Am1W4xHuMHi5yDKCWNXoIN1AlAXSDJ/khlpIzEKaidFi9hguHZwAb06OFc5 oW8fXCVhhLUG7qh7P3JzQk5uu7It/zHLzso2gQwmlWrRvZqr4zt7FfhhdDi/r5eEUxcey21Yu2g/j NEGoNmvw==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wQ4St-003wxJ-0A; Thu, 21 May 2026 14:33:35 +0000 From: Breno Leitao Date: Thu, 21 May 2026 07:32:10 -0700 Subject: [PATCH net v2 2/2] nfc: llcp: read llcp_sock->local under the socket lock in getsockopt Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260521-fix_llc-v2-2-ab44cc09179c@debian.org> References: <20260521-fix_llc-v2-0-ab44cc09179c@debian.org> In-Reply-To: <20260521-fix_llc-v2-0-ab44cc09179c@debian.org> To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , David Heidelberg , Samuel Ortiz Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, oe-linux-nfc@lists.linux.dev, Breno Leitao , kernel-team@meta.com X-Mailer: b4 0.16-dev-d5d98 X-Developer-Signature: v=1; a=openpgp-sha256; l=1449; i=leitao@debian.org; h=from:subject:message-id; bh=vUVzwioy7eyITUTnDSAg54tCJT7WpcF3kD1sfAlb9Xg=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBqDxexoLN0vvPGMg5rRL9uOhEDGMg02w+1OAMR1 fP9m9G+cn2JAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCag8XsQAKCRA1o5Of/Hh3 bQq9D/99Rok2FqAlu/B4u7G+xFig/lgnWR56U7HkFxyB/MHLiES5loMrtFTAEnMjR4Fj+bp99Kf 7DdRLBZGTc+4Ag1d/1dADQxkap0Vi1S/fO2/O7HFCNJp6TS/7BjGZ0LfzAiOYaEiCozseK31SKo weejKQabDWL9LNKVxlE6ADyFPeN3aV19Rb8kRqOcDFcspjTRq/hqgWB9JEhav7q12fjyQ4kRdF5 wrPUtycEyPpgodrPHvLpPRNwYuemo+IUfiEqXxHpcl/g2V+NkHCVlKCHQiXPq3AJCXi1dnKYLrl +ZYxvscmKoxzvOLmntpdleQCPmGdfhcRdgu0uIBfxMtQ5g+CeKpa7HKu5UcmytqwfUqTBFj8m5C rIFY4x7kvt5s2Hdt7Jciw/kFDUqTF3GYAnoasuSyG3fK4IYBxn+lc1Yqe7lbfptnPMHjKhohubq XCM8jmX5Bb3tAPbeOxOOTtrnHiawEBY4emqiteF7qEWrUT6+lacR5P13wZtHy3ZSPk5EDmEqEvA vQuFM0CS8vmDDZo2UlehJg5kAEOoicsSVeR1DeB4H1wbvZ7vhOtzMlD/HnorYGC03Uc3UQOFnb+ 0cV9UrbR11QbjafVVMEJf7JxzeGf11pkw2gTpv5itKL/yyulcPsY4AVV4LrJqAZ0Czhp+CO4F29 H5y9RgDpcRQ/V2A== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D X-Debian-User: leitao 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 --- 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 aa9a78a671521..266590d402664 100644 --- a/net/nfc/llcp_sock.c +++ b/net/nfc/llcp_sock.c @@ -325,14 +325,16 @@ 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-Meta