On Thu, Sep 2, 2021 at 9:32 AM Tim Gardner <[email protected]> wrote:
>
> Coverity complains that linux-next commit 67d6d681e15b5 ("ipv4: make
> exception cache less predictible") neglected to check for NULL before
> dereferencing 'oldest'. It appears to be possible to fall through the for
> loop without ever setting 'oldest'.
Coverity is wrong.
fnhe_remove_oldest() is only called when there are at least 6 items
in the list.
There is no way oldest could be NULL, or that oldest_p could contain garbage.
>
> Cc: Eric Dumazet <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Hideaki YOSHIFUJI <[email protected]>
> Cc: David Ahern <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Tim Gardner <[email protected]>
> ---
> net/ipv4/route.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index d6899ab5fb39..e85026591a09 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -603,9 +603,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash)
> oldest_p = fnhe_p;
> }
> }
> - fnhe_flush_routes(oldest);
> - *oldest_p = oldest->fnhe_next;
> - kfree_rcu(oldest, rcu);
> + if (oldest) {
> + fnhe_flush_routes(oldest);
> + *oldest_p = oldest->fnhe_next;
> + kfree_rcu(oldest, rcu);
> + }
> }
>
> static u32 fnhe_hashfun(__be32 daddr)
> --
> 2.33.0
>
On 9/2/21 9:38 AM, Eric Dumazet wrote:
> On Thu, Sep 2, 2021 at 9:32 AM Tim Gardner <[email protected]> wrote:
>>
>> Coverity complains that linux-next commit 67d6d681e15b5 ("ipv4: make
>> exception cache less predictible") neglected to check for NULL before
>> dereferencing 'oldest'. It appears to be possible to fall through the for
>> loop without ever setting 'oldest'.
>
> Coverity is wrong.
>
> fnhe_remove_oldest() is only called when there are at least 6 items
> in the list.
>
> There is no way oldest could be NULL, or that oldest_p could contain garbage.
>
+1