Re: CVE-2024-49995: tipc: guard against string buffer overrun

[Simon Horman <horms@kernel.org>]

- me at corigine.com
+ netdev

On Thu, Apr 24, 2025 at 11:41:01AM +0530, Harshit Mogalapalli wrote:
> Hi,
> 
> On 21/10/24 23:33, Greg Kroah-Hartman wrote:
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > tipc: guard against string buffer overrun
> > 
> > Smatch reports that copying media_name and if_name to name_parts may
> > overwrite the destination.
> > 
> >   .../bearer.c:166 bearer_name_validate() error: strcpy() 'media_name' too large for 'name_parts->media_name' (32 vs 16)
> >   .../bearer.c:167 bearer_name_validate() error: strcpy() 'if_name' too large for 'name_parts->if_name' (1010102 vs 16)
> > 
> > This does seem to be the case so guard against this possibility by using
> > strscpy() and failing if truncation occurs.
> > 
> > Introduced by commit b97bf3fd8f6a ("[TIPC] Initial merge")
> > 
> > Compile tested only.
> > 
> > The Linux kernel CVE team has assigned CVE-2024-49995 to this issue.
> > 
> > 
> 
> Looking at the fix commit with more lines around the fix:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6555a2a9212be6983d2319d65276484f7c5f431a&context=30
> 
> 
>  	/* validate component parts of bearer name */
>  	if ((media_len <= 1) || (media_len > TIPC_MAX_MEDIA_NAME) ||
>  	    (if_len <= 1) || (if_len > TIPC_MAX_IF_NAME))
>  		return 0;
> 
>  	/* return bearer name components, if necessary */
>  	if (name_parts) {
> -		strcpy(name_parts->media_name, media_name);
> -		strcpy(name_parts->if_name, if_name);
> +		if (strscpy(name_parts->media_name, media_name,
> +			    TIPC_MAX_MEDIA_NAME) < 0)
> +			return 0;
> +		if (strscpy(name_parts->if_name, if_name,
> +			    TIPC_MAX_IF_NAME) < 0)
> +			return 0;
>  	}
>  	return 1;
> 
> 
> 
> both media_len and if_len have validation checks above the if(name_parts)
> check. So I think this patch just silences the static checker warnings.
> 
> Simon/Dan , could you please help confirming that ?

Thanks Harshit,

Looking over this with fresh eyes this morning I agree with your analysis.

I can't be sure what I was thinking regarding this being a bug when I
posted the patch in August. But that it was for net-next, rather than net,
and had no Fixes tag, indicates that I did not feel that it was a bug fix at
the time.

https://lore.kernel.org/netdev/20240801-tipic-overrun-v2-1-c5b869d1f074@kernel.org/

In any case, I don't think it is a bug fix now.


> 
> Thanks,
> Harshit
> 
> > Affected and fixed versions
> > ===========================
> > 
> > 	Fixed in 5.10.227 with commit e2b2558971e0
> > 	Fixed in 5.15.168 with commit 54dae0e9063e
> > 	Fixed in 6.1.113 with commit 80c0be7bcf94
> > 	Fixed in 6.6.55 with commit 12d26aa7fd3c
> > 	Fixed in 6.10.14 with commit 2ed7f42dfd3e
> > 	Fixed in 6.11.3 with commit a18c7b239d02
> > 	Fixed in 6.12-rc1 with commit 6555a2a9212b
> > 
> > Please see https://www.kernel.org for a full list of currently supported
> > kernel versions by the kernel community.
> > 
> > Unaffected versions might change over time as fixes are backported to
> > older supported kernel versions.  The official CVE entry at
> > 	https://cve.org/CVERecord/?id=CVE-2024-49995
> > will be updated if fixes are backported, please check that for the most
> > up to date information about this issue.
> > 
> > 
> > Affected files
> > ==============
> > 
> > The file(s) affected by this issue are:
> > 	net/tipc/bearer.c
> > 
> > 
> > Mitigation
> > ==========
> > 
> > The Linux kernel CVE team recommends that you update to the latest
> > stable kernel version for this, and many other bugfixes.  Individual
> > changes are never tested alone, but rather are part of a larger kernel
> > release.  Cherry-picking individual commits is not recommended or
> > supported by the Linux kernel community at all.  If however, updating to
> > the latest release is impossible, the individual changes to resolve this
> > issue can be found at these commits:
> > 	https://git.kernel.org/stable/c/e2b2558971e02ca33eb637a8350d68a48b3e8e46
> > 	https://git.kernel.org/stable/c/54dae0e9063ed23c9acf8d5ab9b18d3426a8ac18
> > 	https://git.kernel.org/stable/c/80c0be7bcf940ce9308311575c3aff8983c9b97a
> > 	https://git.kernel.org/stable/c/12d26aa7fd3cbdbc5149b6e516563478d575026e
> > 	https://git.kernel.org/stable/c/2ed7f42dfd3edb387034128ca5b0f639836d4ddd
> > 	https://git.kernel.org/stable/c/a18c7b239d02aafb791ae2c45226f6bb40641792
> > 	https://git.kernel.org/stable/c/6555a2a9212be6983d2319d65276484f7c5f431a
>