[PATCH bpf-next v3 2/2] bpf: Check return from set_memory_rox()
Martin KaFai Lau
martin.lau at linux.dev
Fri Mar 15 17:56:24 PDT 2024
On 3/15/24 2:11 PM, Martin KaFai Lau wrote:
> On 3/15/24 1:55 PM, Martin KaFai Lau wrote:
>> On 3/15/24 10:06 AM, Christophe Leroy wrote:
>>> diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
>>> index 43356faaa057..ca1d9b87c475 100644
>>> --- a/kernel/bpf/bpf_struct_ops.c
>>> +++ b/kernel/bpf/bpf_struct_ops.c
>>> @@ -742,8 +742,11 @@ static long bpf_struct_ops_map_update_elem(struct
>>> bpf_map *map, void *key,
>>> if (err)
>>> goto reset_unlock;
>>> }
>>> - for (i = 0; i < st_map->image_pages_cnt; i++)
>>> - arch_protect_bpf_trampoline(st_map->image_pages[i], PAGE_SIZE);
>>> + for (i = 0; i < st_map->image_pages_cnt && !err; i++)
I was about to apply but I still think checking "&& !err" is not right given how
"err" is used in the earlier code of this function.
The err may not be 0 in the first iteration of this for loop. Take a look at the
"if (err > 0)" check in the "for_each_member(i, t, member)" loop above.
>>> + err = arch_protect_bpf_trampoline(st_map->image_pages[i], PAGE_SIZE);
>>> +
>>> + if (err)
>>> + goto reset_unlock;
>>
>> This part does not look right. The "if (err)" check should be inside the for
>> loop.
Instead of adding an extra "err = 0;" before the for loop. It is better to move
this "if (err) goto reset_unlock;" into the for loop and remove the "&& !err"
test above.
>
> ah. Please ignore. missed the "!err" in the for loop.
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