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 53D2839DBD4; Thu, 17 Sep 2026 18:56:05 +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=1789671366; cv=none; b=WDSmFwjbGIezLdedAbMAF3M3JOisnc0g4325Rr7AURKAb2GyOUpQqJBZ6pCnUSdVKn/7guPw2LD2UhfQuadEVszivfmjpHKzkaPBlZTj57xfe14eYNA5BHNcUhi2xfFFsTLlzeet+W/jvQ1CUoiQo62pqeeejbqfLfMB2bSFoxQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789671366; c=relaxed/simple; bh=ZE8q5N+cwN6TKzeuWVwzhf51d8IGYHdEScz87oIXLa0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qwtto3wNEL1wQ+NWq5CCKi1GMN5RSETQflBFsYDgn4V3U+4OrExmXdiG2s8YgXdoR0gxItAMbIXOE+WA1UQa+OY+jhF/QDk50iLhrxugjKIP14PAbRM/9sSDS6M5dKm5Q0zl95DdKgP1AJUJ1iEuH6BQ6xWq9J022j+QJJYzXrE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OwIcYOjZ; 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="OwIcYOjZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 593E71F000FF; Thu, 17 Sep 2026 18:56:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789671364; bh=RyJ+go/msiurJFboCsvOubOSnUYq9WpevgR/l2bOlkc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OwIcYOjZPJA9eL/3vS21+7U8uT6OnVAHff5l2xBGK923ykUMJCBj1JyWhyqXzYCG+ 0brPQE+GSUTaiqgiPJCZ+s5K1kQoKV0ox7X44W6S5+pREPI3z9OtJ9qeSwqFauWl1w aADHFh7Nexd50jCtiRB1X0QH5xm7rfR9LLNEr//Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Jakub Kicinski Subject: [PATCH 6.12 0951/1102] net: appletalk: fix NULL pointer dereference in aarp_send_ddp() Date: Thu, 17 Sep 2026 16:14:54 +0100 Message-ID: <20260917151604.532344778@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151539.408551884@linuxfoundation.org> References: <20260917151539.408551884@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weiming Shi commit 9e7f36ab5b7bf68463faa5f7b926fea8f35597bb upstream. aarp_send_ddp() calls atalk_find_dev_addr(dev) in the LocalTalk fast path without checking for NULL. When the device has no AppleTalk interface configured (dev->atalk_ptr == NULL), this leads to a NULL pointer dereference at the at->s_net access. KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:aarp_send_ddp (net/appletalk/aarp.c:552 (discriminator 2)) Call Trace: atalk_sendmsg (net/appletalk/ddp.c:1715) __sys_sendto (net/socket.c:2265 (discriminator 1)) __x64_sys_sendto (net/socket.c:2272) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Add a NULL check consistent with the other callers of atalk_find_dev_addr(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Link: https://patch.msgid.link/20260514123806.3085961-3-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/appletalk/aarp.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/appletalk/aarp.c +++ b/net/appletalk/aarp.c @@ -573,6 +573,11 @@ int aarp_send_ddp(struct net_device *dev struct ddpehdr *ddp = (struct ddpehdr *)skb->data; int ft = 2; + if (!at) { + kfree_skb(skb); + return NET_XMIT_DROP; + } + /* * Compressible ? *