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| author | Yazhou Tang <tangyazhou518@outlook.com> | 2026-03-04 11:32:28 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-03-10 21:46:31 +0300 |
| commit | ea1989746b77c3f63bce43af247e1de29ed6bf4a (patch) | |
| tree | 415d069e0d969278640f7ad13bfd394836c569c8 | |
| parent | a3125bc01884431d30d731461634c8295b6f0529 (diff) | |
| download | linux-ea1989746b77c3f63bce43af247e1de29ed6bf4a.tar.xz | |
selftests/bpf: Add test for BPF_END register ID reset
Add a test case to ensure that BPF_END operations correctly break
register's scalar ID ties.
The test creates a scenario where r1 is a copy of r0, r0 undergoes a
byte swap, and then r0 is checked against a constant.
- Without the fix in the verifier, the bounds learned from r0 are
incorrectly propagated to r1, making the verifier believe r1 is
bounded and wrongly allowing subsequent pointer arithmetic.
- With the fix, r1 remains an unbounded scalar, and the verifier
correctly rejects the arithmetic operation between the frame pointer
and the unbounded register.
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260304083228.142016-3-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_bswap.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_bswap.c b/tools/testing/selftests/bpf/progs/verifier_bswap.c index 4b779deee767..cffaf36192bc 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bswap.c +++ b/tools/testing/selftests/bpf/progs/verifier_bswap.c @@ -91,6 +91,28 @@ BSWAP_RANGE_TEST(le32_range, "le32", 0x3f00, 0x3f0000) BSWAP_RANGE_TEST(le64_range, "le64", 0x3f00, 0x3f000000000000) #endif +SEC("socket") +__description("BSWAP, reset reg id") +__failure __msg("math between fp pointer and register with unbounded min value is not allowed") +__naked void bswap_reset_reg_id(void) +{ + asm volatile (" \ + call %[bpf_ktime_get_ns]; \ + r1 = r0; \ + r0 = be16 r0; \ + if r0 != 1 goto l0_%=; \ + r2 = r10; \ + r2 += -512; \ + r2 += r1; \ + *(u8 *)(r2 + 0) = 0; \ +l0_%=: \ + r0 = 0; \ + exit; \ +" : + : __imm(bpf_ktime_get_ns) + : __clobber_all); +} + #else SEC("socket") |