Commit 85eb035e authored by Hao Sun's avatar Hao Sun Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add test for immediate spilled to stack 



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: default avatarHao Sun <sunhao.th@gmail.com>
Link: https://lore.kernel.org/r/20231101-fix-check-stack-write-v3-2-f05c2b1473d5@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 811c3636

tools/testing/selftests/bpf/verifier/bpf_st_mem.c

+32 −0
Original line number Diff line number Diff line
@@ -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",

},