diff options
| author | Edward Cree | 2017-08-23 16:10:03 +0200 |
|---|---|---|
| committer | David S. Miller | 2017-08-24 07:38:07 +0200 |
| commit | 63f45f840634ab5fd71bbc07acff915277764068 (patch) | |
| tree | cb362e59b70cfb3188d10329713764452009257e /kernel/bpf/verifier.c | |
| parent | selftests/bpf: add a test for a bug in liveness-based pruning (diff) | |
| download | kernel-qcow2-linux-63f45f840634ab5fd71bbc07acff915277764068.tar.gz kernel-qcow2-linux-63f45f840634ab5fd71bbc07acff915277764068.tar.xz kernel-qcow2-linux-63f45f840634ab5fd71bbc07acff915277764068.zip | |
bpf/verifier: when pruning a branch, ignore its write marks
The fact that writes occurred in reaching the continuation state does
not screen off its reads from us, because we're not really its parent.
So detect 'not really the parent' in do_propagate_liveness, and ignore
write marks in that case.
Fixes: dc503a8ad984 ("bpf/verifier: track liveness for pruning")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e42c096ba20d..fdbaa6086559 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3436,6 +3436,7 @@ out_free: static bool do_propagate_liveness(const struct bpf_verifier_state *state, struct bpf_verifier_state *parent) { + bool writes = parent == state->parent; /* Observe write marks */ bool touched = false; /* any changes made? */ int i; @@ -3447,7 +3448,9 @@ static bool do_propagate_liveness(const struct bpf_verifier_state *state, for (i = 0; i < BPF_REG_FP; i++) { if (parent->regs[i].live & REG_LIVE_READ) continue; - if (state->regs[i].live == REG_LIVE_READ) { + if (writes && (state->regs[i].live & REG_LIVE_WRITTEN)) + continue; + if (state->regs[i].live & REG_LIVE_READ) { parent->regs[i].live |= REG_LIVE_READ; touched = true; } @@ -3460,7 +3463,9 @@ static bool do_propagate_liveness(const struct bpf_verifier_state *state, continue; if (parent->spilled_regs[i].live & REG_LIVE_READ) continue; - if (state->spilled_regs[i].live == REG_LIVE_READ) { + if (writes && (state->spilled_regs[i].live & REG_LIVE_WRITTEN)) + continue; + if (state->spilled_regs[i].live & REG_LIVE_READ) { parent->spilled_regs[i].live |= REG_LIVE_READ; touched = true; } |