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Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

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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>
This commit is contained in:
David S. Miller 2019-09-07 09:52:29 +02:00
commit 0c04eb72d3
1 changed files with 14 additions and 9 deletions
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23
kernel/bpf/verifier.c
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@ -1772,16 +1772,21 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno,
bitmap_from_u64(mask, stack_mask); bitmap_from_u64(mask, stack_mask);
for_each_set_bit(i, mask, 64) { for_each_set_bit(i, mask, 64) {
if (i >= func->allocated_stack / BPF_REG_SIZE) { if (i >= func->allocated_stack / BPF_REG_SIZE) {
/* This can happen if backtracking /* the sequence of instructions:
* is propagating stack precision where * 2: (bf) r3 = r10
* caller has larger stack frame * 3: (7b) *(u64 *)(r3 -8) = r0
* than callee, but backtrack_insn() should * 4: (79) r4 = *(u64 *)(r10 -8)
* have returned -ENOTSUPP. * 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", mark_all_scalars_precise(env, st);
i, func->allocated_stack); return 0;
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
} }
if (func->stack[i].slot_type[0] != STACK_SPILL) { if (func->stack[i].slot_type[0] != STACK_SPILL) {