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selftests/bpf: Verify copy_register_state() preserves parent/live fields

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[ Upstream commit b9fa9bc839 ]

A testcase to check that verifier.c:copy_register_state() preserves
register parentage chain and livness information.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230106142214.1040390-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eduard Zingerman 2023-01-06 16:22:14 +02:00 committed by Greg Kroah-Hartman
parent 7814e28c41
commit 5541d35f5d
1 changed files with 36 additions and 0 deletions
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36
tools/testing/selftests/bpf/verifier/search_pruning.c
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@ -154,3 +154,39 @@
.result_unpriv = ACCEPT,
.insn_processed = 15,
},
/* The test performs a conditional 64-bit write to a stack location
* fp[-8], this is followed by an unconditional 8-bit write to fp[-8],
* then data is read from fp[-8]. This sequence is unsafe.
*
* The test would be mistakenly marked as safe w/o dst register parent
* preservation in verifier.c:copy_register_state() function.
*
* Note the usage of BPF_F_TEST_STATE_FREQ to force creation of the
* checkpoint state after conditional 64-bit assignment.
*/
{
"write tracking and register parent chain bug",
.insns = {
/* r6 = ktime_get_ns() */
BPF_EMIT_CALL(BPF_FUNC_ktime_get_ns),
BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
/* r0 = ktime_get_ns() */
BPF_EMIT_CALL(BPF_FUNC_ktime_get_ns),
/* if r0 > r6 goto +1 */
BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_6, 1),
/* *(u64 *)(r10 - 8) = 0xdeadbeef */
BPF_ST_MEM(BPF_DW, BPF_REG_FP, -8, 0xdeadbeef),
/* r1 = 42 */
BPF_MOV64_IMM(BPF_REG_1, 42),
/* *(u8 *)(r10 - 8) = r1 */
BPF_STX_MEM(BPF_B, BPF_REG_FP, BPF_REG_1, -8),
/* r2 = *(u64 *)(r10 - 8) */
BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_FP, -8),
/* exit(0) */
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.flags = BPF_F_TEST_STATE_FREQ,
.errstr = "invalid read from stack off -8+1 size 8",
.result = REJECT,
},