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| author | Andrii Nakryiko <andrii@kernel.org> | 2023-11-18 06:46:23 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-11-18 22:39:59 +0300 |
| commit | 46862ee854b4f5a315d63b677ca3af14a89aefeb (patch) | |
| tree | c9df3007d849646ad84684b894fa8350a6d8e949 /kernel/bpf/log.c | |
| parent | 0f8dbdbc641b45a5fa31d497f9fc83ffe1174fa3 (diff) | |
| download | linux-46862ee854b4f5a315d63b677ca3af14a89aefeb.tar.xz | |
bpf: emit frameno for PTR_TO_STACK regs if it differs from current one
It's possible to pass a pointer to parent's stack to child subprogs. In
such case verifier state output is ambiguous not showing whether
register container a pointer to "current" stack, belonging to current
subprog (frame), or it's actually a pointer to one of parent frames.
So emit this information if frame number differs between the state which
register is part of. E.g., if current state is in frame 2 and it has
a register pointing to stack in grand parent state (frame #0), we'll see
something like 'R1=fp[0]-16', while "local stack pointer" will be just
'R2=fp-16'.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/log.c')
| -rw-r--r-- | kernel/bpf/log.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 87105aa482ed..3505f3e5ae96 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -615,7 +615,9 @@ static bool type_is_map_ptr(enum bpf_reg_type t) { } } -static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) +static void print_reg_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state, + const struct bpf_reg_state *reg) { enum bpf_reg_type t; const char *sep = ""; @@ -623,10 +625,8 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s t = reg->type; if (t == SCALAR_VALUE && reg->precise) verbose(env, "P"); - if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && - tnum_is_const(reg->var_off)) { + if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) { /* reg->off should be 0 for SCALAR_VALUE */ - verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); verbose_snum(env, reg->var_off.value + reg->off); return; } @@ -637,6 +637,14 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s #define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, ##__VA_ARGS__); sep = ","; }) verbose(env, "%s", reg_type_str(env, t)); + if (t == PTR_TO_STACK) { + if (state->frameno != reg->frameno) + verbose(env, "[%d]", reg->frameno); + if (tnum_is_const(reg->var_off)) { + verbose_snum(env, reg->var_off.value + reg->off); + return; + } + } if (base_type(t) == PTR_TO_BTF_ID) verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); verbose(env, "("); @@ -698,7 +706,7 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " R%d", i); print_liveness(env, reg->live); verbose(env, "="); - print_reg_state(env, reg); + print_reg_state(env, state, reg); } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; @@ -731,7 +739,7 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); verbose(env, "=%s", types_buf); - print_reg_state(env, reg); + print_reg_state(env, state, reg); break; case STACK_DYNPTR: /* skip to main dynptr slot */ |