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 E41ED158538; Tue, 16 Dec 2025 07:11:17 +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=1765869078; cv=none; b=prXWjQReQUvGMA2BD67U/No9uf5ELe16ANqe7EDRjim3JvbjA5uJcofdsi5uCJrgrThg1XtfMujF54zL37tHifkq3psFmj2FsoloLSPBY9RTzHDTMJPFoxneCNMRCTh5SWHwGbp0++oOOsL87QDQJgZyLy4Rvql3RtrZBMucrog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765869078; c=relaxed/simple; bh=fa0zgiC6/KfmKqs37/xhEKTiioKlQhOHMyFCK890XW4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=R6eq6kNHRu4GkeTtVVgRmFODLA0rYEzwMU5fYHIYJBiAaJk70XdCy5IVnap2oZmZWSsdm4s2gBXxml2R5NHv9Am1r5oZO62MUzDODmYxgC2aAiG4/8/DZs1zlxCx2y6l1rDF+j5U17tLS3jc+y1PiPx1cEE+XoccjrnJKD8QnDs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KdcNRo1P; 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="KdcNRo1P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97CB3C4CEF1; Tue, 16 Dec 2025 07:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765869076; bh=fa0zgiC6/KfmKqs37/xhEKTiioKlQhOHMyFCK890XW4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KdcNRo1Pf5tXBBHEsPzhlOvkk6Iz1Pw4F0OZe8FqH9sSo0F4sCNZYZAkTUD5pTUTo 0PVNWGz+ivbql3mtjebM0zEepuGU6I2luXKzIK4S8pJg7Np0CaAVm4KvOYiaIrvoDP CbGV+Hw5G2lfMXKxZx9HCGhWvpyvPNUF0H8/OW2eImrYy0e6DPVSlM4T9AMFGt5LSu ewlKETUCK20rfCA9uj/9vXvExaZD8QZoyVyFXbaUJehClQVYVIiJ3c1xU1K6NI5WLE 2EAvvHrju7jouaP0Kl+ns7/nnU5sWgTjA4rT8iqGZ7RKR3vKbrt6GMLKp1bx7k2gPa nGPBGm4knedUw== Message-ID: <243ec26f-1fe1-4b3c-ab24-a6ebab163cde@kernel.org> Date: Tue, 16 Dec 2025 08:11:13 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] w1: therm: Fix off-by-one buffer overflow in alarms_store To: Thorsten Blum , David Laight , Huisong Li , Akira Shimahara , Greg Kroah-Hartman Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251111204422.41993-2-thorsten.blum@linux.dev> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/11/2025 21:44, Thorsten Blum wrote: > The sysfs buffer passed to alarms_store() is allocated with 'size + 1' > bytes and a NUL terminator is appended. However, the 'size' argument > does not account for this extra byte. The original code then allocated > 'size' bytes and used strcpy() to copy 'buf', which always writes one > byte past the allocated buffer since strcpy() copies until the NUL > terminator at index 'size'. > > Fix this by parsing the 'buf' parameter directly using simple_strtoll() > without allocating any intermediate memory or string copying. This > removes the overflow while simplifying the code. > > Cc: stable@vger.kernel.org > Fixes: e2c94d6f5720 ("w1_therm: adding alarm sysfs entry") > Signed-off-by: Thorsten Blum > --- > Compile-tested only. > > Changes in v4: > - Use simple_strtoll because kstrtoint also parses long long internally > - Return -ERANGE in addition to -EINVAL to match kstrtoint's behavior > - Remove any changes unrelated to fixing the buffer overflow (Krzysztof) > while maintaining the same behavior and return values as before > - Link to v3: https://lore.kernel.org/lkml/20251030155614.447905-1-thorsten.blum@linux.dev/ > > Changes in v3: > - Add integer range check for 'temp' to match kstrtoint() behavior > - Explicitly cast 'temp' to int when calling int_to_short() > - Link to v2: https://lore.kernel.org/lkml/20251029130045.70127-2-thorsten.blum@linux.dev/ > > Changes in v2: > - Fix buffer overflow instead of truncating the copy using strscpy() > - Parse buffer directly using simple_strtol() as suggested by David > - Update patch subject and description > - Link to v1: https://lore.kernel.org/lkml/20251017170047.114224-2-thorsten.blum@linux.dev/ > --- > drivers/w1/slaves/w1_therm.c | 64 ++++++++++++------------------------ > 1 file changed, 21 insertions(+), 43 deletions(-) > > diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c > index 9ccedb3264fb..5707fa34e804 100644 > --- a/drivers/w1/slaves/w1_therm.c > +++ b/drivers/w1/slaves/w1_therm.c > @@ -1836,55 +1836,36 @@ static ssize_t alarms_store(struct device *device, > struct w1_slave *sl = dev_to_w1_slave(device); > struct therm_info info; > u8 new_config_register[3]; /* array of data to be written */ > - int temp, ret; > - char *token = NULL; > + long long temp; > + int ret = 0; > s8 tl, th; /* 1 byte per value + temp ring order */ > - char *p_args, *orig; > - > - p_args = orig = kmalloc(size, GFP_KERNEL); > - /* Safe string copys as buf is const */ > - if (!p_args) { > - dev_warn(device, > - "%s: error unable to allocate memory %d\n", > - __func__, -ENOMEM); > - return size; > - } > - strcpy(p_args, buf); > - > - /* Split string using space char */ > - token = strsep(&p_args, " "); > - > - if (!token) { > - dev_info(device, > - "%s: error parsing args %d\n", __func__, -EINVAL); > - goto free_m; > - } > - > - /* Convert 1st entry to int */ > - ret = kstrtoint (token, 10, &temp); > + const char *p = buf; > + char *endp; > + > + temp = simple_strtoll(p, &endp, 10); Why using this, instead of explicitly encouraged kstrtoll()? > + if (p == endp || *endp != ' ') > + ret = -EINVAL; > + else if (temp < INT_MIN || temp > INT_MAX) > + ret = -ERANGE; > if (ret) { > dev_info(device, > "%s: error parsing args %d\n", __func__, ret); > - goto free_m; > + goto err; So this is just return size. Best regards, Krzysztof