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selftests/bpf: Add tests with stack ptr register in conditional jmp

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Add two tests:
  - one test has 'rX <op> r10' where rX is not r10, and
  - another test has 'rX <op> rY' where rX and rY are not r10
    but there is an early insn 'rX = r10'.

Without previous verifier change, both tests will fail.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250524041340.4046304-1-yonghong.song@linux.dev
This commit is contained in:
Yonghong Song
2025-05-27 14:09:12 -07:00
committed by Andrii Nakryiko
parent e2d2115e56
commit 5ffb537e41
2 changed files with 58 additions and 2 deletions
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kernel/bpf/verifier.c
+5 -2
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@@ -16456,6 +16456,8 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
if (src_reg->type == PTR_TO_STACK)
insn_flags |= INSN_F_SRC_REG_STACK;
if (dst_reg->type == PTR_TO_STACK)
insn_flags |= INSN_F_DST_REG_STACK;
} else {
if (insn->src_reg != BPF_REG_0) {
verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
@@ -16465,10 +16467,11 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
memset(src_reg, 0, sizeof(*src_reg));
src_reg->type = SCALAR_VALUE;
__mark_reg_known(src_reg, insn->imm);
if (dst_reg->type == PTR_TO_STACK)
insn_flags |= INSN_F_DST_REG_STACK;
}
if (dst_reg->type == PTR_TO_STACK)
insn_flags |= INSN_F_DST_REG_STACK;
if (insn_flags) {
err = push_insn_history(env, this_branch, insn_flags, 0);
if (err)