Re: [PATCH bpf-next v9 02/23] bpf/verifier: do not clear meta in check_mem_size
From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Date: 2022-08-26 01:55:30
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On Wed, 24 Aug 2022 at 15:41, Benjamin Tissoires [off-list ref] wrote:
quoted hunk ↗ jump to hunk
The purpose of this clear is to prevent meta->raw_mode to be evaluated at true, but this also prevents to forward any other data to the other callees. Only switch back raw_mode to false so we don't entirely clear meta. Acked-by: Yonghong Song <redacted> Signed-off-by: Benjamin Tissoires <redacted> --- no changes in v9 no changes in v8 no changes in v7 new in v6 --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d694f43ab911..13190487fb12 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c@@ -5287,7 +5287,7 @@ static int check_mem_size_reg(struct bpf_verifier_env *env, * initialize all the memory that the helper could * just partially fill up. */ - meta = NULL; + meta->raw_mode = false;
But this is adding a side effect, the caller's meta->raw_mode becomes false, which the caller may not expect...
if (reg->smin_value < 0) {
verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
--
2.36.1