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author | Jose E. Marchesi <jose.marchesi@oracle.com> | 2024-05-07 21:47:56 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-06-27 14:52:15 +0300 |
commit | f6824c5a98bcd6c8dc1161cf1a09c00147dd3dd3 (patch) | |
tree | 007df674b18845994d0cbfaaf62a86fa756c5d09 /tools | |
parent | 27d93808761f921d536ea6a80425324aeffa3980 (diff) | |
download | linux-f6824c5a98bcd6c8dc1161cf1a09c00147dd3dd3.tar.xz |
bpf: avoid uninitialized warnings in verifier_global_subprogs.c
[ Upstream commit cd3fc3b9782130a5bc1dc3dfccffbc1657637a93 ]
[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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'tools')
-rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_global_subprogs.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c b/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c index baff5ffe9405..a9fc30ed4d73 100644 --- a/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c +++ b/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c @@ -8,6 +8,13 @@ #include "xdp_metadata.h" #include "bpf_kfuncs.h" +/* The compiler may be able to detect the access to uninitialized + memory in the routines performing out of bound memory accesses and + emit warnings about it. This is the case of GCC. */ +#if !defined(__clang__) +#pragma GCC diagnostic ignored "-Wmaybe-uninitialized" +#endif + int arr[1]; int unkn_idx; const volatile bool call_dead_subprog = false; |