From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 672B34C6EEC; Mon, 20 Apr 2026 13:33:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691983; cv=none; b=OVM3VffyL8B7evL3n32x1u7LqdwWBA1vW9zgyhXBqz16kkPL0+iahLBkhci2wWaChHmQ/GSYuaowXMNt6jhokdAA1jPxztwz57dkAUcc1fFT8goeEQZgVjS9Xhx9AOkyYuhV5YIMBeKnZt2a2KGoezTADwgVqjsNdsuK2ULju9I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691983; c=relaxed/simple; bh=G4rr8t+cL1IGQWS7XAHaJ3u+HohH4a1o5NALoiHwlgY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=msd3W23el9kvyJ5G/wR5QE3A/QhQHX0oOt+wMrWzzlwIg9ms0miI2qe3siVzTyvV/+x8Lz+ymv8XSwxY3oDm6d+IRg6eLe8FubdPaXTpx/px4yIRqGLW3WKxbpECbFrIRcMEqP1HnIy/7YfXG5IpIDxaOi+Mb5DabNDYytZySPI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bcarKyyC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bcarKyyC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58804C2BCB4; Mon, 20 Apr 2026 13:33:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776691983; bh=G4rr8t+cL1IGQWS7XAHaJ3u+HohH4a1o5NALoiHwlgY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bcarKyyC2bFbZ/0y7L340sLrPL+jfDV3xBkYb6wTGNV/RMTp43dDOAxTH4bUTjMVX teCU8IaojAE5VB7L13Gt5wTPZmR47lTqre4yZggr6sY5TVgJC4gROgL/H+2ML6RBoB jepQORGTc7caM3vr5PEXaSjl6SVyUTp7R1b3o3Q8efYFBx4Cf1NtLZ/d9PhL+/euyy nLJZVJWI9Z/JfPbGVapuhL/jQ7lVlUQv4RBNn7Cc5qpwggXiNMrbZplIRfEaweSXAk 06VpY1aLNdQUs4P76B9li2ElM/F4+ypb5kPK4w4T2oaZz3KimIWMu2n91vg27NWKXG /pRlebxa5ghuQ== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Pengpeng Hou , Jakub Kicinski , Sasha Levin , krzk@kernel.org, bongsu.jeon@samsung.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 6.18] nfc: s3fwrn5: allocate rx skb before consuming bytes Date: Mon, 20 Apr 2026 09:21:39 -0400 Message-ID: <20260420132314.1023554-305-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420132314.1023554-1-sashal@kernel.org> References: <20260420132314.1023554-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.18.23 Content-Transfer-Encoding: 8bit From: Pengpeng Hou [ Upstream commit 5c14a19d5b1645cce1cb1252833d70b23635b632 ] s3fwrn82_uart_read() reports the number of accepted bytes to the serdev core. The current code consumes bytes into recv_skb and may already deliver a complete frame before allocating a fresh receive buffer. If that alloc_skb() fails, the callback returns 0 even though it has already consumed bytes, and it leaves recv_skb as NULL for the next receive callback. That breaks the receive_buf() accounting contract and can also lead to a NULL dereference on the next skb_put_u8(). Allocate the receive skb lazily before consuming the next byte instead. If allocation fails, return the number of bytes already accepted. Fixes: 3f52c2cb7e3a ("nfc: s3fwrn5: Support a UART interface") Signed-off-by: Pengpeng Hou Link: https://patch.msgid.link/20260402042148.65236-1-pengpeng@iscas.ac.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: Error: Failed to generate final synthesis drivers/nfc/s3fwrn5/uart.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/nfc/s3fwrn5/uart.c b/drivers/nfc/s3fwrn5/uart.c index 9c09c10c2a464..4ee481bd7e965 100644 --- a/drivers/nfc/s3fwrn5/uart.c +++ b/drivers/nfc/s3fwrn5/uart.c @@ -58,6 +58,12 @@ static size_t s3fwrn82_uart_read(struct serdev_device *serdev, size_t i; for (i = 0; i < count; i++) { + if (!phy->recv_skb) { + phy->recv_skb = alloc_skb(NCI_SKB_BUFF_LEN, GFP_KERNEL); + if (!phy->recv_skb) + return i; + } + skb_put_u8(phy->recv_skb, *data++); if (phy->recv_skb->len < S3FWRN82_NCI_HEADER) @@ -69,9 +75,7 @@ static size_t s3fwrn82_uart_read(struct serdev_device *serdev, s3fwrn5_recv_frame(phy->common.ndev, phy->recv_skb, phy->common.mode); - phy->recv_skb = alloc_skb(NCI_SKB_BUFF_LEN, GFP_KERNEL); - if (!phy->recv_skb) - return 0; + phy->recv_skb = NULL; } return i; -- 2.53.0