lkml.org 
[lkml]   [2021]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] rxrpc: fix handling of an unsupported token type in rxrpc_read()
From
Date

On 1/6/21 9:40 AM, David Howells wrote:
> David Howells <dhowells@redhat.com> wrote:
>
>> How about this?
>> ...
>> Fix the second loop so that it doesn't encode the size and type of an
>> unsupported token, but rather just ignore it as does the first loop.
> Actually, a better way is probably just to error out in this case. This
> should only happen if a new token type is incompletely implemented.
>
> David
> ---
> commit e68ef16f59aa57564761b21e5ecb2ebbd72d1c57
> Author: David Howells <dhowells@redhat.com>
> Date: Wed Jan 6 16:21:40 2021 +0000
>
> rxrpc: Fix handling of an unsupported token type in rxrpc_read()
>
> Clang static analysis reports the following:
>
> net/rxrpc/key.c:657:11: warning: Assigned value is garbage or undefined
> toksize = toksizes[tok++];
> ^ ~~~~~~~~~~~~~~~
>
> rxrpc_read() contains two consecutive loops. The first loop calculates the
> token sizes and stores the results in toksizes[] and the second one uses
> the array. When there is an error in identifying the token in the first
> loop, the token is skipped, no change is made to the toksizes[] array.
> When the same error happens in the second loop, the token is not skipped.
> This will cause the toksizes[] array to be out of step and will overrun
> past the calculated sizes.
>
> Fix this by making both loops log a message and return an error in this
> case. This should only happen if a new token type is incompletely
> implemented, so it should normally be impossible to trigger this.
>
> Fixes: 9a059cd5ca7d ("rxrpc: Downgrade the BUG() for unsupported token type in rxrpc_read()")
> Reported-by: Tom Rix <trix@redhat.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
>
> diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
> index 9631aa8543b5..8d2073e0e3da 100644
> --- a/net/rxrpc/key.c
> +++ b/net/rxrpc/key.c
> @@ -598,7 +598,7 @@ static long rxrpc_read(const struct key *key,
> default: /* we have a ticket we can't encode */
> pr_err("Unsupported key token type (%u)\n",
> token->security_index);
> - continue;
> + return -ENOPKG;
> }

These two loops iterate over the same data, i believe returning here is all that is needed.

Tom

>
> _debug("token[%u]: toksize=%u", ntoks, toksize);
> @@ -674,7 +674,9 @@ static long rxrpc_read(const struct key *key,
> break;
>
> default:
> - break;
> + pr_err("Unsupported key token type (%u)\n",
> + token->security_index);
> + return -ENOPKG;
> }
>
> ASSERTCMP((unsigned long)xdr - (unsigned long)oldxdr, ==,
>

\
 
 \ /
  Last update: 2021-01-06 20:36    [W:0.109 / U:0.364 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site