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selftests/bpf: Silence array bounds warning in global_map_resize

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When compiling BPF selftests with -O2, GCC reports an array bounds
violation warning in global_map_resize test:

    In function ‘global_map_resize_bss_subtest’,
        inlined from ‘test_global_map_resize’ at /bpf-next/tools/testing/selftests/bpf/prog_tests/global_map_resize.c:228:3:
    /bpf-next/tools/testing/selftests/bpf/prog_tests/global_map_resize.c:64:33: error: array subscript 1 is above array bounds of ‘int[1]’ [-Werror=array-bounds=]
       64 |                 skel->bss->array[i] = 1;
          |                 ~~~~~~~~~~~~~~~~^~~
    In file included from /bpf-next/tools/testing/selftests/bpf/prog_tests/global_map_resize.c:6:
    ./test_global_map_resize.skel.h: In function ‘test_global_map_resize’:
    ./test_global_map_resize.skel.h:44:21: note: while referencing ‘array’
       44 |                 int array[1];
          |                     ^~~~~

This is a false positive because `array` (a BPF map) has been resized
from within the BPF program. GCC doesn't know that so let us silence the
warning by accessing the array via a plain pointer.

Fixes: 08b0895675 ("libbpf: Selftests for resizing datasec maps")
Signed-off-by: Viktor Malik <vmalik@redhat.com>
Link: https://lore.kernel.org/bpf/57765bc465a27923c3c093eba222cc24d08d8c40.1784112948.git.vmalik@redhat.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
This commit is contained in:
Viktor Malik
2026-07-15 13:22:02 +02:00
committed by Kumar Kartikeya Dwivedi
parent eb5cd154f1
commit dcd164ec67
1 changed files with 6 additions and 2 deletions
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8
tools/testing/selftests/bpf/prog_tests/global_map_resize.c
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@@ -23,6 +23,7 @@ static void global_map_resize_bss_subtest(void)
struct bpf_map *map;
const __u32 desired_sz = sizeof(skel->bss->sum) + sysconf(_SC_PAGE_SIZE) * 2;
size_t array_len, actual_sz, new_sz;
int *array;
skel = test_global_map_resize__open();
if (!ASSERT_OK_PTR(skel, "test_global_map_resize__open"))
@@ -58,10 +59,13 @@ static void global_map_resize_bss_subtest(void)
goto teardown;
/* fill the newly resized array with ones,
* skipping the first element which was previously set
* skipping the first element which was previously set;
* access through a plain pointer to avoid -Warray-bounds
* since the array was resized beyond its declared length.
*/
array = skel->bss->array;
for (int i = 1; i < array_len; i++)
skel->bss->array[i] = 1;
array[i] = 1;
/* set global const values before loading */
skel->rodata->pid = getpid();