From: Edward Cree ecree@solarflare.com
mainline inclusion from mainline-v4.20-rc1 commit 8efea21d333d21e1f9177579ffdc69556314f603 category: feature bugzilla: 43460 CVE: NA
--------------------------------------- If a stack slot does not hold a spilled register (STACK_SPILL), then each of its eight bytes could potentially have a different slot_type. This information can be important for debugging, and previously we either did not print anything for the stack slot, or just printed fp-X=0 in the case where its first byte was STACK_ZERO. Instead, print eight characters with either 0 (STACK_ZERO), m (STACK_MISC) or ? (STACK_INVALID) for any stack slot which is neither STACK_SPILL nor entirely STACK_INVALID.
Signed-off-by: Edward Cree ecree@solarflare.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: liuxin liuxin264@huawei.com Reviewed-by: Cheng Jian cj.chengjian@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- kernel/bpf/verifier.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2fa3e269fe1d..f58e7928768a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -263,6 +263,13 @@ static const char * const reg_type_str[] = { [PTR_TO_PACKET_END] = "pkt_end", };
+static char slot_type_char[] = { + [STACK_INVALID] = '?', + [STACK_SPILL] = 'r', + [STACK_MISC] = 'm', + [STACK_ZERO] = '0', +}; + static void print_liveness(struct bpf_verifier_env *env, enum bpf_reg_liveness live) { @@ -349,15 +356,26 @@ static void print_verifier_state(struct bpf_verifier_env *env, } } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { - if (state->stack[i].slot_type[0] == STACK_SPILL) { - verbose(env, " fp%d", - (-i - 1) * BPF_REG_SIZE); - print_liveness(env, state->stack[i].spilled_ptr.live); + char types_buf[BPF_REG_SIZE + 1]; + bool valid = false; + int j; + + for (j = 0; j < BPF_REG_SIZE; j++) { + if (state->stack[i].slot_type[j] != STACK_INVALID) + valid = true; + types_buf[j] = slot_type_char[ + state->stack[i].slot_type[j]]; + } + types_buf[BPF_REG_SIZE] = 0; + if (!valid) + continue; + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, state->stack[i].spilled_ptr.live); + if (state->stack[i].slot_type[0] == STACK_SPILL) verbose(env, "=%s", reg_type_str[state->stack[i].spilled_ptr.type]); - } - if (state->stack[i].slot_type[0] == STACK_ZERO) - verbose(env, " fp%d=0", (-i - 1) * BPF_REG_SIZE); + else + verbose(env, "=%s", types_buf); } verbose(env, "\n"); }