Re: [PATCH bpf-next v3 01/11] selftests/bpf: Fix caps for __xlated/jited_unpriv

From: Eduard Zingerman
Date: Thu May 01 2025 - 13:45:56 EST


On Thu, 2025-05-01 at 09:35 +0200, Luis Gerhorst wrote:
> Currently, __xlated_unpriv and __jited_unpriv do not work because the
> BPF syscall will overwrite info.jited_prog_len and info.xlated_prog_len
> with 0 if the process is not bpf_capable(). This bug was not noticed
> before, because there is no test that actually uses
> __xlated_unpriv/__jited_unpriv.
>
> To resolve this, simply restore the capabilities earlier (but still
> after loading the program). Adding this here unconditionally is fine
> because the function first checks that the capabilities were initialized
> before attempting to restore them.
>
> This will be important later when we add tests that check whether a
> speculation barrier was inserted in the correct location.
>
> Signed-off-by: Luis Gerhorst <luis.gerhorst@xxxxxx>
> Fixes: 9c9f73391310 ("selftests/bpf: allow checking xlated programs in verifier_* tests")
> Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit")
> ---

My bad, thank you for fixing this omission.

Tested-by: Eduard Zingerman <eddyz87@xxxxxxxxx>