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| author | David S. Miller <davem@davemloft.net> | 2019-09-07 09:52:29 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-09-07 09:52:29 +0200 |
| commit | 0c04eb72d332ef6e12c3ecb0c638359e65ad29d9 (patch) | |
| tree | 1f304aa698332029f711dbaf2d7b131df60ee6ba | |
| parent | 74346c434cd24cce73d971da950f0b5b82bac0d6 (diff) | |
| parent | 2339cd6cd0b5401fa3fe886bf1c0cb8822041957 (diff) | |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Alexei Starovoitov says:
====================
pull-request: bpf 2019-09-06
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) verifier precision tracking fix, from Alexei.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | kernel/bpf/verifier.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b5c14c9d7b98..c36a719fee6d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1772,16 +1772,21 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, bitmap_from_u64(mask, stack_mask); for_each_set_bit(i, mask, 64) { if (i >= func->allocated_stack / BPF_REG_SIZE) { - /* This can happen if backtracking - * is propagating stack precision where - * caller has larger stack frame - * than callee, but backtrack_insn() should - * have returned -ENOTSUPP. + /* the sequence of instructions: + * 2: (bf) r3 = r10 + * 3: (7b) *(u64 *)(r3 -8) = r0 + * 4: (79) r4 = *(u64 *)(r10 -8) + * doesn't contain jmps. It's backtracked + * as a single block. + * During backtracking insn 3 is not recognized as + * stack access, so at the end of backtracking + * stack slot fp-8 is still marked in stack_mask. + * However the parent state may not have accessed + * fp-8 and it's "unallocated" stack space. + * In such case fallback to conservative. */ - verbose(env, "BUG spi %d stack_size %d\n", - i, func->allocated_stack); - WARN_ONCE(1, "verifier backtracking bug"); - return -EFAULT; + mark_all_scalars_precise(env, st); + return 0; } if (func->stack[i].slot_type[0] != STACK_SPILL) { |