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bpf: verifier: mark patched-insn with sub-register zext flag

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Patched insns do not go through generic verification, therefore doesn't has
zero extension information collected during insn walking.

We don't bother analyze them at the moment, for any sub-register def comes
from them, just conservatively mark it as needing zero extension.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiong Wang 2019-05-24 23:25:13 +01:00 committed by Alexei Starovoitov
parent 5327ed3d44
commit b325fbca4b
1 changed files with 33 additions and 4 deletions
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37
kernel/bpf/verifier.c
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@ -1269,6 +1269,24 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
return true;
}
/* Return TRUE if INSN doesn't have explicit value define. */
static bool insn_no_def(struct bpf_insn *insn)
{
u8 class = BPF_CLASS(insn->code);
return (class == BPF_JMP || class == BPF_JMP32 ||
class == BPF_STX || class == BPF_ST);
}
/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
if (insn_no_def(insn))
return false;
return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP);
}
static void mark_insn_zext(struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
@ -7298,14 +7316,23 @@ static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
* [0, off) and [off, end) to new locations, so the patched range stays zero
*/
static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
u32 off, u32 cnt)
static int adjust_insn_aux_data(struct bpf_verifier_env *env,
struct bpf_prog *new_prog, u32 off, u32 cnt)
{
struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
struct bpf_insn *insn = new_prog->insnsi;
u32 prog_len;
int i;
/* aux info at OFF always needs adjustment, no matter fast path
* (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
* original insn at old prog.
*/
old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);
if (cnt == 1)
return 0;
prog_len = new_prog->len;
new_data = vzalloc(array_size(prog_len,
sizeof(struct bpf_insn_aux_data)));
if (!new_data)
@ -7313,8 +7340,10 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
memcpy(new_data + off + cnt - 1, old_data + off,
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
for (i = off; i < off + cnt - 1; i++)
for (i = off; i < off + cnt - 1; i++) {
new_data[i].seen = true;
new_data[i].zext_dst = insn_has_def32(env, insn + i);
}
env->insn_aux_data = new_data;
vfree(old_data);
return 0;
@ -7347,7 +7376,7 @@ static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of
env->insn_aux_data[off].orig_idx);
return NULL;
}
if (adjust_insn_aux_data(env, new_prog->len, off, len))
if (adjust_insn_aux_data(env, new_prog, off, len))
return NULL;
adjust_subprog_starts(env, off, len);
return new_prog;