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-rw-r--r--kernel/bpf/verifier.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a2e763703c30..def87e9cc9c7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1519,9 +1519,9 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx,
return -EFAULT;
}
*stack_mask |= 1ull << spi;
- } else if (class == BPF_STX) {
+ } else if (class == BPF_STX || class == BPF_ST) {
if (*reg_mask & dreg)
- /* stx shouldn't be using _scalar_ dst_reg
+ /* stx & st shouldn't be using _scalar_ dst_reg
* to access memory. It means backtracking
* encountered a case of pointer subtraction.
*/
@@ -1540,7 +1540,8 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx,
if (!(*stack_mask & (1ull << spi)))
return 0;
*stack_mask &= ~(1ull << spi);
- *reg_mask |= sreg;
+ if (class == BPF_STX)
+ *reg_mask |= sreg;
} else if (class == BPF_JMP || class == BPF_JMP32) {
if (opcode == BPF_CALL) {
if (insn->src_reg == BPF_PSEUDO_CALL)
@@ -1569,10 +1570,6 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx,
if (mode == BPF_IND || mode == BPF_ABS)
/* to be analyzed */
return -ENOTSUPP;
- } else if (class == BPF_ST) {
- if (*reg_mask & dreg)
- /* likely pointer subtraction */
- return -ENOTSUPP;
}
return 0;
}