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

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 2025-05-23 21:13:40 -07:00 committed by Andrii Nakryiko
parent e2d2115e56
commit 5ffb537e41
2 changed files with 58 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/bpf/verifier.c
View File

@ -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)

53
tools/testing/selftests/bpf/progs/verifier_precision.c
View File

@ -178,4 +178,57 @@ __naked int state_loop_first_last_equal(void)
);
}
__used __naked static void __bpf_cond_op_r10(void)
{
asm volatile (
"r2 = 2314885393468386424 ll;"
"goto +0;"
"if r2 <= r10 goto +3;"
"if r1 >= -1835016 goto +0;"
"if r2 <= 8 goto +0;"
"if r3 <= 0 goto +0;"
"exit;"
::: __clobber_all);
}
SEC("?raw_tp")
__success __log_level(2)
__msg("8: (bd) if r2 <= r10 goto pc+3")
__msg("9: (35) if r1 >= 0xffe3fff8 goto pc+0")
__msg("10: (b5) if r2 <= 0x8 goto pc+0")
__msg("mark_precise: frame1: last_idx 10 first_idx 0 subseq_idx -1")
__msg("mark_precise: frame1: regs=r2 stack= before 9: (35) if r1 >= 0xffe3fff8 goto pc+0")
__msg("mark_precise: frame1: regs=r2 stack= before 8: (bd) if r2 <= r10 goto pc+3")
__msg("mark_precise: frame1: regs=r2 stack= before 7: (05) goto pc+0")
__naked void bpf_cond_op_r10(void)
{
asm volatile (
"r3 = 0 ll;"
"call __bpf_cond_op_r10;"
"r0 = 0;"
"exit;"
::: __clobber_all);
}
SEC("?raw_tp")
__success __log_level(2)
__msg("3: (bf) r3 = r10")
__msg("4: (bd) if r3 <= r2 goto pc+1")
__msg("5: (b5) if r2 <= 0x8 goto pc+2")
__msg("mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1")
__msg("mark_precise: frame0: regs=r2 stack= before 4: (bd) if r3 <= r2 goto pc+1")
__msg("mark_precise: frame0: regs=r2 stack= before 3: (bf) r3 = r10")
__naked void bpf_cond_op_not_r10(void)
{
asm volatile (
"r0 = 0;"
"r2 = 2314885393468386424 ll;"
"r3 = r10;"
"if r3 <= r2 goto +1;"
"if r2 <= 8 goto +2;"
"r0 = 2 ll;"
"exit;"
::: __clobber_all);
}
char _license[] SEC("license") = "GPL";