diff options
| author | Alban Crequy <albancrequy@linux.microsoft.com> | 2022-11-10 09:56:14 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-11-11 11:44:46 -0800 |
| commit | 9cd094829dae949a755c18533479c20e74415ab2 (patch) | |
| tree | 09a8c1c050975d07822ecdf5fb8197be912d20c0 | |
| parent | 8678ea06852cd1f819b870c773d43df888d15d46 (diff) | |
selftests: bpf: Add a test when bpf_probe_read_kernel_str() returns EFAULT
This commit tests previous fix of bpf_probe_read_kernel_str().
The BPF helper bpf_probe_read_kernel_str should return -EFAULT when
given a bad source pointer and the target buffer should only be modified
to make the string NULL terminated.
bpf_probe_read_kernel_str() was previously inserting a NULL before the
beginning of the dst buffer. This test should ensure that the
implementation stays correct for now on.
Without the fix, this test will fail as follows:
$ cd tools/testing/selftests/bpf
$ make
$ sudo ./test_progs --name=varlen
...
test_varlen:FAIL:check got 0 != exp 66
Signed-off-by: Alban Crequy <albancrequy@linux.microsoft.com>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221110085614.111213-3-albancrequy@linux.microsoft.com
Changes v1 to v2:
- add ack tag
- fix my email
- rebase on bpf tree and tag for bpf tree
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/varlen.c | 7 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_varlen.c | 5 |
2 files changed, 12 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/varlen.c b/tools/testing/selftests/bpf/prog_tests/varlen.c index dd324b4933db..4d7056f8f177 100644 --- a/tools/testing/selftests/bpf/prog_tests/varlen.c +++ b/tools/testing/selftests/bpf/prog_tests/varlen.c @@ -63,6 +63,13 @@ void test_varlen(void) CHECK_VAL(data->total4, size1 + size2); CHECK(memcmp(data->payload4, exp_str, size1 + size2), "content_check", "doesn't match!\n"); + + CHECK_VAL(bss->ret_bad_read, -EFAULT); + CHECK_VAL(data->payload_bad[0], 0x42); + CHECK_VAL(data->payload_bad[1], 0x42); + CHECK_VAL(data->payload_bad[2], 0); + CHECK_VAL(data->payload_bad[3], 0x42); + CHECK_VAL(data->payload_bad[4], 0x42); cleanup: test_varlen__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/test_varlen.c b/tools/testing/selftests/bpf/progs/test_varlen.c index 3987ff174f1f..20eb7d422c41 100644 --- a/tools/testing/selftests/bpf/progs/test_varlen.c +++ b/tools/testing/selftests/bpf/progs/test_varlen.c @@ -19,6 +19,7 @@ __u64 payload1_len1 = 0; __u64 payload1_len2 = 0; __u64 total1 = 0; char payload1[MAX_LEN + MAX_LEN] = {}; +__u64 ret_bad_read = 0; /* .data */ int payload2_len1 = -1; @@ -36,6 +37,8 @@ int payload4_len2 = -1; int total4= -1; char payload4[MAX_LEN + MAX_LEN] = { 1 }; +char payload_bad[5] = { 0x42, 0x42, 0x42, 0x42, 0x42 }; + SEC("raw_tp/sys_enter") int handler64_unsigned(void *regs) { @@ -61,6 +64,8 @@ int handler64_unsigned(void *regs) total1 = payload - (void *)payload1; + ret_bad_read = bpf_probe_read_kernel_str(payload_bad + 2, 1, (void *) -1); + return 0; } |