On 8/12/24 11:41 AM, Eduard Zingerman wrote:
On Mon, 2024-08-12 at 11:36 -0700, Yonghong Song wrote:
[...]
Sorry, I copy-paste from 'git diff' result to my email window. Not sure
why it caused the format issue after I sent out.
Sure, no problem
Anyway, the following is the patch I suggested:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index df3be12096cf..1906798f1a3d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -17338,10 +17338,13 @@ static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
*/
for (i = 0; i < old->allocated_stack; i++) {
struct bpf_reg_state *old_reg, *cur_reg;
+ bool cur_exceed_bound;
spi = i / BPF_REG_SIZE;
- if (exact != NOT_EXACT &&
+ cur_exceed_bound = i >= cur->allocated_stack;
idk, I think C compiler would do this anyways,
to me the code is fine both with and without this additional variable.
Okay, I will keep the original (simpler) patch then.
+
+ if (exact != NOT_EXACT && !cur_exceed_bound &&
old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
cur->stack[spi].slot_type[i % BPF_REG_SIZE])
return false;
@@ -17363,7 +17366,7 @@ static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
/* explored stack has more populated slots than current stack
* and these slots were used
*/
- if (i >= cur->allocated_stack)
+ if (cur_exceed_bound)
return false;
/* 64-bit scalar spill vs all slots MISC and vice versa.
