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selftests/bpf: Add test for immediate spilled to stack

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Add a test to check if the verifier correctly reason about the sign
of an immediate spilled to stack by BPF_ST instruction.

Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Link: https://lore.kernel.org/r/20231101-fix-check-stack-write-v3-2-f05c2b1473d5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hao Sun 2023-11-01 13:33:52 +01:00 committed by Alexei Starovoitov
parent 811c363645
commit 85eb035e6c
1 changed files with 32 additions and 0 deletions
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32
tools/testing/selftests/bpf/verifier/bpf_st_mem.c
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@ -65,3 +65,35 @@
.expected_attach_type = BPF_SK_LOOKUP,
.runs = -1,
},
{
"BPF_ST_MEM stack imm sign",
/* Check if verifier correctly reasons about sign of an
* immediate spilled to stack by BPF_ST instruction.
*
* fp[-8] = -44;
* r0 = fp[-8];
* if r0 s< 0 goto ret0;
* r0 = -1;
* exit;
* ret0:
* r0 = 0;
* exit;
*/
.insns = {
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, -44),
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
BPF_JMP_IMM(BPF_JSLT, BPF_REG_0, 0, 2),
BPF_MOV64_IMM(BPF_REG_0, -1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
/* Use prog type that requires return value in range [0, 1] */
.prog_type = BPF_PROG_TYPE_SK_LOOKUP,
.expected_attach_type = BPF_SK_LOOKUP,
.result = VERBOSE_ACCEPT,
.runs = -1,
.errstr = "0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44\
2: (c5) if r0 s< 0x0 goto pc+2\
R0_w=-44",
},