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SubjectRe: [PATCH 1/2] bpf: sockmap, fix uninitialized variable
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Hi John,

On 05/17/2018 12:27 PM, John Fastabend wrote:
> On 05/17/2018 07:08 AM, Gustavo A. R. Silva wrote:
>> There is a potential execution path in which variable err is
>> returned without being properly initialized previously.
>>
>> Fix this by initializing variable err to 0.
>>
>> Addresses-Coverity-ID: 1468964 ("Uninitialized scalar variable")
>> Fixes: e5cd3abcb31a ("bpf: sockmap, refactor sockmap routines to work
>> with hashmap")
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>> ---
>> kernel/bpf/sockmap.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
>> index c6de139..41b41fc 100644
>> --- a/kernel/bpf/sockmap.c
>> +++ b/kernel/bpf/sockmap.c
>> @@ -1713,7 +1713,7 @@ static int __sock_map_ctx_update_elem(struct bpf_map *map,
>> struct smap_psock_map_entry *e = NULL;
>> struct smap_psock *psock;
>> bool new = false;
>> - int err;
>> + int err = 0;
>>
>> /* 1. If sock map has BPF programs those will be inherited by the
>> * sock being added. If the sock is already attached to BPF programs
>>
>
> Thanks for catching this and the quick fix. The path to hit this case
> is to add a sock to a map (without a BPF program) where the sock already
> has been added to another map. I don't have any tests for the case with
> socks in multiple maps so I'll add some to the selftests so I remember
> this case.
>

Glad to help. :)

> The alternative fix would be to always 'return 0' at the end of the
> function, but I think its probably better to init err here like above.
>

Yeah. I think initializing err is better in this case.

> Acked-by: John Fastabend <john.fastabend@gmail.com>
>

Thank you
--
Gustavo

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