[Changes from V1:
- The warning to disable is -Wmaybe-uninitialized, not -Wuninitialized.
- This warning is only supported in GCC.]
The BPF selftest verifier_global_subprogs.c contains code that
purposedly performs out of bounds access to memory, to check whether
the kernel verifier is able to catch them. For example:
__noinline int global_unsupp(const int *mem)
{
if (!mem)
return 0;
return mem[100]; /* BOOM */
}
With -O1 and higher and no inlining, GCC notices this fact and emits a
"maybe uninitialized" warning. This is by design. Note that the
emission of these warnings is highly dependent on the precise
optimizations that are performed.
This patch adds a compiler pragma to verifier_global_subprogs.c to
ignore these warnings.
Tested in bpf-next master.
No regressions.
Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Cc: david.faust@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240507184756.1772-1-jose.marchesi@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a bunch of global subprogs across variety of program types to
validate expected kernel type enforcement logic for __arg_ctx arguments.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add selftest that establishes dead code-eliminated valid global subprog
(global_dead) and makes sure that it's not possible to freplace it, as
it's effectively not there. This test will fail with unexpected success
before 2afae08c9d ("bpf: Validate global subprogs lazily").
v2->v3:
- add missing err assignment (Alan);
- undo unnecessary signature changes in verifier_global_subprogs.c (Eduard);
v1->v2:
- don't rely on assembly output in verifier log, which changes between
compiler versions (CI).
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20231211174131.2324306-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a few test that validate BPF verifier's lazy approach to validating
global subprogs.
We check that global subprogs that are called transitively through
another global subprog is validated.
We also check that invalid global subprog is not validated, if it's not
called from the main program.
And we also check that main program is always validated first, before
any of the subprogs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-4-andrii@kernel.org
