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selftests/bpf: precision of a NULL global subprogram memory argument

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Check that mark_chain_precision() is called for a NULL pointer passed
as a nullable pointer argument of a global subprogram.
(Pointer arguments of the global subprograms are nullable by default).

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-4-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman
2026-09-04 17:05:55 -07:00
committed by Alexei Starovoitov
parent f1e418129f
commit 100f4cc0d5
1 changed files with 32 additions and 0 deletions
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32
tools/testing/selftests/bpf/progs/verifier_precision.c
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@@ -676,4 +676,36 @@ __naked int null_mem_arg_zero_size(void)
: __clobber_all);
}
__weak int subprog_mem_arg(int *p)
{
if (p)
return *p;
return 0;
}
/*
* Verification takes two paths: with r1 being scalar zero on path (1)
* and with r1 being some other scalar on path (2).
* Check that the verifier does not use checkpoints created
* on path (1) to prune path (2).
*/
SEC("?raw_tp")
__flag(BPF_F_TEST_STATE_FREQ)
__failure __msg("R1 type=scalar expected=fp")
__naked int null_mem_arg_global_subprog(void)
{
asm volatile (
"call %[bpf_get_prandom_u32];"
"r1 = 42;"
"if r0 > 42 goto 1f;"
"r1 = 0;"
"1:"
"call subprog_mem_arg;"
"r0 = 0;"
"exit;"
:
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
char _license[] SEC("license") = "GPL";