From: Eduard Zingerman <eddyz87@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>,
bpf@vger.kernel.org, ast@kernel.org
Cc: andrii@kernel.org, martin.lau@linux.dev, kernel-team@fb.com, yhs@fb.com
Subject: Re: [PATCH bpf-next 0/2] Allow reads from uninit stack
Date: Fri, 17 Feb 2023 22:46:05 +0200 [thread overview]
Message-ID: <fe4e2cf65d39ded9c6948ccf43e593eb29ab9753.camel@gmail.com> (raw)
In-Reply-To: <98d4936a-27de-95b3-d787-40b78654916d@iogearbox.net>
On Fri, 2023-02-17 at 21:37 +0100, Daniel Borkmann wrote:
[...]
> Ptal, looks like BPF CI is complaining:
>
> https://github.com/kernel-patches/bpf/actions/runs/4205832876/jobs/7298488977
>
Yes, I messed up comments in the asm blocks when replaced '\n\' line
endings with '\' before sending the patch w/o re-testing.
Sorry about that.
I'm waiting for answers from Andrii and will resend the patch-set.
---
Here is how the tests should look like:
/* Read an uninitialized value from stack at a fixed offset */
SEC("socket")
__naked int read_uninit_stack_fixed_off(void *ctx)
{
asm volatile (" \
r0 = 0; \
/* force stack depth to be 128 */ \
*(u64*)(r10 - 128) = r1; \
r1 = *(u8 *)(r10 - 8 ); \
r0 += r1; \
r1 = *(u8 *)(r10 - 11); \
r1 = *(u8 *)(r10 - 13); \
r1 = *(u8 *)(r10 - 15); \
r1 = *(u16*)(r10 - 16); \
r1 = *(u32*)(r10 - 32); \
r1 = *(u64*)(r10 - 64); \
/* read from a spill of a wrong size, it is a separate \
* branch in check_stack_read_fixed_off() \
*/ \
*(u32*)(r10 - 72) = r1; \
r1 = *(u64*)(r10 - 72); \
r0 = 0; \
exit; \
"
::: __clobber_all);
}
/* Read an uninitialized value from stack at a variable offset */
SEC("socket")
__naked int read_uninit_stack_var_off(void *ctx)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
/* force stack depth to be 64 */ \
*(u64*)(r10 - 64) = r0; \
r0 = -r0; \
/* give r0 a range [-31, -1] */ \
if r0 s<= -32 goto exit_%=; \
if r0 s>= 0 goto exit_%=; \
/* access stack using r0 */ \
r1 = r10; \
r1 += r0; \
r2 = *(u8*)(r1 + 0); \
exit_%=: r0 = 0; \
exit; \
"
:
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
[...]
prev parent reply other threads:[~2023-02-17 20:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 18:36 [PATCH bpf-next 0/2] Allow reads from uninit stack Eduard Zingerman
2023-02-16 18:36 ` [PATCH bpf-next 1/2] bpf: " Eduard Zingerman
2023-02-17 0:36 ` Andrii Nakryiko
2023-02-17 13:13 ` Eduard Zingerman
2023-02-17 21:58 ` Andrii Nakryiko
2023-02-16 18:36 ` [PATCH bpf-next 2/2] selftests/bpf: Tests for uninitialized stack reads Eduard Zingerman
2023-02-17 0:55 ` Andrii Nakryiko
2023-02-17 13:25 ` Eduard Zingerman
2023-02-17 22:00 ` Andrii Nakryiko
2023-02-17 22:06 ` Eduard Zingerman
2023-02-17 20:37 ` [PATCH bpf-next 0/2] Allow reads from uninit stack Daniel Borkmann
2023-02-17 20:46 ` Eduard Zingerman [this message]
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