Re: [PATCH] keys, dns: Fix size check of V1 server-list header

[Petr Vorel]

From: Sedat Dilek <sedat.dilek@xxxxxxxxx>

On Wed, Jan 10, 2024 at 10:12 PM David Howells <dhowells@xxxxxxxxxx> wrote:
>
>
> Fix the size check added to dns_resolver_preparse() for the V1 server-list
> header so that it doesn't give EINVAL if the size supplied is the same as
> the size of the header struct (which should be valid).
>
> This can be tested with:
>
>         echo -n -e '\0\0\01\xff\0\0' | keyctl padd dns_resolver desc @p
>
> which will give "add_key: Invalid argument" without this fix.
>
> Fixes: 1997b3cb4217 ("keys, dns: Fix missing size check of V1 server-list header")

[ CC stable@xxxxxxxxxxxxxxx ]

Your (follow-up) patch is now upstream.

https://git.kernel.org/linus/acc657692aed438e9931438f8c923b2b107aebf9

This misses CC: Stable Tag as suggested by Linus.

Looks like linux-6.1.y and linux-6.6.y needs it, too.

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.6.11&id=da89365158f6f656b28bcdbcbbe9eaf97c63c474
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.72&id=079eefaecfd7bbb8fcc30eccb0dfdf50c91f1805

BG,
-Sedat-

Hi Greg, Sasa,

could you please add this also to linux-6.1.y and linux-6.6.y?  (Easily
applicable to both, needed for both.) Or is there any reason why it's not
being added?

Kind regards,
Petr

> Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
> Link: https://lore.kernel.org/r/ZZ4fyY4r3rqgZL+4@xxxxxxxxxxxxxxxx/
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Edward Adam Davis <eadavis@xxxxxx>
> cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> cc: Simon Horman <horms@xxxxxxxxxx>
> Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> Cc: Jeffrey E Altman <jaltman@xxxxxxxxxxxx>
> Cc: Wang Lei <wang840925@xxxxxxxxx>
> Cc: Jeff Layton <jlayton@xxxxxxxxxx>
> Cc: Steve French <sfrench@xxxxxxxxxx>
> Cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> ---
>  net/dns_resolver/dns_key.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
> index f18ca02aa95a..c42ddd85ff1f 100644
> --- a/net/dns_resolver/dns_key.c
> +++ b/net/dns_resolver/dns_key.c
> @@ -104,7 +104,7 @@ dns_resolver_preparse(struct key_preparsed_payload *prep)
>                 const struct dns_server_list_v1_header *v1;
>
>                 /* It may be a server list. */
> -               if (datalen <= sizeof(*v1))
> +               if (datalen < sizeof(*v1))
>                         return -EINVAL;
>
>                 v1 = (const struct dns_server_list_v1_header *)data;
>
>