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[LTS RT 8.8] bpf: Fix incorrect verifier pruning due to missing register precision… #99

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Merged
merged 1 commit into from
Feb 4, 2025
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[LTS RT 8.8] bpf: Fix incorrect verifier pruning due to missing register precision… #99

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15 changes: 15 additions & 0 deletions kernel/bpf/verifier.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2224,6 +2224,21 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx,
}
} else if (opcode == BPF_EXIT) {
return -ENOTSUPP;
} else if (BPF_SRC(insn->code) == BPF_X) {
if (!(*reg_mask & (dreg | sreg)))
return 0;
/* dreg <cond> sreg
* Both dreg and sreg need precision before
* this insn. If only sreg was marked precise
* before it would be equally necessary to
* propagate it to dreg.
*/
*reg_mask |= (sreg | dreg);
/* else dreg <cond> K
* Only dreg still needs precision before
* this insn, so for the K-based conditional
* there is nothing new to be marked.
*/
}
} else if (class == BPF_LD) {
if (!(*reg_mask & dreg))
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