netdev - RE: [Intel-wired-lan] [PATCH] i40e: replace snprintf() with scnprintf()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <PH3PPF7A88A980A3D6E4FD4E6D0E9179E95E55CA@PH3PPF7A88A980A.namprd11.prod.outlook.com>
Date: Tue, 22 Jul 2025 15:57:14 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: Amir Mohammad Jahangirzad <a.jahangirzad@...il.com>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, "andrew+netdev@...n.ch"
	<andrew+netdev@...n.ch>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH] i40e: replace snprintf() with
 scnprintf()



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Amir Mohammad Jahangirzad
> Sent: Tuesday, July 22, 2025 1:50 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@...el.com>; andrew+netdev@...n.ch;
> davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> pabeni@...hat.com
> Cc: intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; Amir Mohammad Jahangirzad
> <a.jahangirzad@...il.com>
> Subject: [Intel-wired-lan] [PATCH] i40e: replace snprintf() with
> scnprintf()
> 
> In i40e_dbg_command_read(), a 256-byte buffer is allocated and filled
> using snprintf(), then copied to userspace via copy_to_user().
> 
> The issue is that snprintf() returns the number of characters that
> *Would* have been written, not the number that actually fit in the
> buffer.
> If the combined length of the netdev name and i40e_dbg_command_buf is
> long (e.g. 288 + 3 bytes), snprintf() still returns 291 - even though
> only
> 256 bytes were written.
> 
> This value is passed to copy_to_user(), which may read past the end of
> the buffer and leak kernel memory to userspace.
> 
> Replacing snprintf() with scnprintf() fixes this. It returns the
> actual number of bytes written, ensuring we only copy valid data.
> 
Can you add 'Fixes:' tag?
And I think this patch should be directed to [Intel-wired-lan] [PATCH iwl-net]
To be backported to all LTS kernels.

> Signed-off-by: Amir Mohammad Jahangirzad <a.jahangirzad@...il.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_debugfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
> b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
> index 6cd9da662ae1..19a78052800f 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
> @@ -70,7 +70,7 @@ static ssize_t i40e_dbg_command_read(struct file
> *filp, char __user *buffer,
>  		return -ENOSPC;
> 
>  	main_vsi = i40e_pf_get_main_vsi(pf);
> -	len = snprintf(buf, buf_size, "%s: %s\n", main_vsi->netdev-
> >name,
> +	len = scnprintf(buf, buf_size, "%s: %s\n", main_vsi->netdev-
> >name,
>  		       i40e_dbg_command_buf);
> 
>  	bytes_not_copied = copy_to_user(buffer, buf, len);
> --
> 2.43.0