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selftests/bpf: Add three test cases for bits_iter

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Add more test cases for bits iterator:

(1) huge word test
Verify the multiplication overflow of nr_bits in bits_iter. Without
the overflow check, when nr_words is 67108865, nr_bits becomes 64,
causing bpf_probe_read_kernel_common() to corrupt the stack.
(2) max word test
Verify correct handling of maximum nr_words value (511).
(3) bad word test
Verify early termination of bits iteration when bits iterator
initialization fails.

Also rename bits_nomem to bits_too_big to better reflect its purpose.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2024-10-30 18:05:16 +08:00 committed by Alexei Starovoitov
parent e133938367
commit ebafc1e535
1 changed files with 58 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

61
tools/testing/selftests/bpf/progs/verifier_bits_iter.c
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@ -15,6 +15,8 @@ int bpf_iter_bits_new(struct bpf_iter_bits *it, const u64 *unsafe_ptr__ign,
int *bpf_iter_bits_next(struct bpf_iter_bits *it) __ksym __weak;
void bpf_iter_bits_destroy(struct bpf_iter_bits *it) __ksym __weak;
u64 bits_array[511] = {};
SEC("iter.s/cgroup")
__description("bits iter without destroy")
__failure __msg("Unreleased reference")
@ -110,16 +112,16 @@ int bit_index(void)
}
SEC("syscall")
__description("bits nomem")
__description("bits too big")
__success __retval(0)
int bits_nomem(void)
int bits_too_big(void)
{
u64 data[4];
int nr = 0;
int *bit;
__builtin_memset(&data, 0xff, sizeof(data));
bpf_for_each(bits, bit, &data[0], 513) /* Be greater than 512 */
bpf_for_each(bits, bit, &data[0], 512) /* Be greater than 511 */
nr++;
return nr;
}
@ -151,3 +153,56 @@ int zero_words(void)
nr++;
return nr;
}
SEC("syscall")
__description("huge words")
__success __retval(0)
int huge_words(void)
{
u64 data[8] = {0x1, 0x1, 0x1, 0x1, 0x1, 0x1, 0x1, 0x1};
int nr = 0;
int *bit;
bpf_for_each(bits, bit, &data[0], 67108865)
nr++;
return nr;
}
SEC("syscall")
__description("max words")
__success __retval(4)
int max_words(void)
{
volatile int nr = 0;
int *bit;
bits_array[0] = (1ULL << 63) | 1U;
bits_array[510] = (1ULL << 33) | (1ULL << 32);
bpf_for_each(bits, bit, bits_array, 511) {
if (nr == 0 && *bit != 0)
break;
if (nr == 2 && *bit != 32672)
break;
nr++;
}
return nr;
}
SEC("syscall")
__description("bad words")
__success __retval(0)
int bad_words(void)
{
void *bad_addr = (void *)(3UL << 30);
int nr = 0;
int *bit;
bpf_for_each(bits, bit, bad_addr, 1)
nr++;
bpf_for_each(bits, bit, bad_addr, 4)
nr++;
return nr;
}