Re: [PATCH] Fix compat regression in process_vm_rw()

Jens Axboe
2020-10-27T19:32:37Z

On 10/27/20 1:19 PM, damian wrote:
> On Mo, 26. Okt 18:03, Jens Axboe wrote:
>> The removal of compat_process_vm_{readv,writev} didn't change
>> process_vm_rw(), which always assumes it's not doing a compat syscall.
>> Instead of passing in 'false' unconditionally for 'compat', make it
>> conditional on in_compat_syscall().
>>
>> Fixes: c3973b401ef2 ("mm: remove compat_process_vm_{readv,writev}")
>> Reported-by: Kyle Huey <me@kylehuey.com>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> ---
>>
>> diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
>> index fd12da80b6f2..05676722d9cd 100644
>> --- a/mm/process_vm_access.c
>> +++ b/mm/process_vm_access.c
>> @@ -273,7 +273,8 @@ static ssize_t process_vm_rw(pid_t pid,
>> return rc;
>> if (!iov_iter_count(&iter))
>> goto free_iov_l;
>> - iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r, false);
>> + iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r,
>> + in_compat_syscall());
>> if (IS_ERR(iov_r)) {
>> rc = PTR_ERR(iov_r);
>> goto free_iov_l;
>>
>> --
>> Jens Axboe
>>
> Hello Jens,
>
> i got the following error when i try to build.
>
> m/process_vm_access.c: In Funktion »process_vm_rw«:
> mm/process_vm_access.c:277:5: Fehler: Implizite Deklaration der Funktion »in_compat_syscall«; meinten Sie »in_ia32_syscall«? [-Werror=implicit-function-declaration]
> 277 | in_compat_syscall());
> | ^~~~~~~~~~~~~~~~~
> | in_ia32_syscall

Yeah, sorry about that. Geert sent out a fix:

https://lore.kernel.org/lkml/20201027182246.651908-1-geert+renesas@glider.be/

--
Jens Axboe