summaryrefslogtreecommitdiffstats
path: root/kernel/bpf
diff options
context:
space:
mode:
authorJakub Kicinski <jakub.kicinski@netronome.com>2019-03-21 14:34:36 -0700
committerAlexei Starovoitov <ast@kernel.org>2019-03-21 19:57:02 -0700
commit83d163124cf1104cca5b668d5fe6325715a60855 (patch)
tree0efb88a71d45a495137c28f26eb94575bf28ff2c /kernel/bpf
parent0803278b0b4d8eeb2b461fb698785df65a725d9e (diff)
downloadlinux-83d163124cf1104cca5b668d5fe6325715a60855.tar.bz2
bpf: verifier: propagate liveness on all frames
Commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences") connected up parentage chains of all frames of the stack. It didn't, however, ensure propagate_liveness() propagates all liveness information along those chains. This means pruning happening in the callee may generate explored states with incomplete liveness for the chains in lower frames of the stack. The included selftest is similar to the prior one from commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences"), where callee would prune regardless of the difference in r8 state. Now we also initialize r9 to 0 or 1 based on a result from get_random(). r9 is never read so the walk with r9 = 0 gets pruned (correctly) after the walk with r9 = 1 completes. The selftest is so arranged that the pruning will happen in the callee. Since callee does not propagate read marks of r8, the explored state at the pruning point prior to the callee will now ignore r8. Propagate liveness on all frames of the stack when pruning. Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f19d5e04c69d..fd502c1f71eb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6078,15 +6078,17 @@ static int propagate_liveness(struct bpf_verifier_env *env,
}
/* Propagate read liveness of registers... */
BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
- /* We don't need to worry about FP liveness because it's read-only */
- for (i = 0; i < BPF_REG_FP; i++) {
- if (vparent->frame[vparent->curframe]->regs[i].live & REG_LIVE_READ)
- continue;
- if (vstate->frame[vstate->curframe]->regs[i].live & REG_LIVE_READ) {
- err = mark_reg_read(env, &vstate->frame[vstate->curframe]->regs[i],
- &vparent->frame[vstate->curframe]->regs[i]);
- if (err)
- return err;
+ for (frame = 0; frame <= vstate->curframe; frame++) {
+ /* We don't need to worry about FP liveness, it's read-only */
+ for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
+ if (vparent->frame[frame]->regs[i].live & REG_LIVE_READ)
+ continue;
+ if (vstate->frame[frame]->regs[i].live & REG_LIVE_READ) {
+ err = mark_reg_read(env, &vstate->frame[frame]->regs[i],
+ &vparent->frame[frame]->regs[i]);
+ if (err)
+ return err;
+ }
}
}