netdev - Re: [PATCH bpf] bpf: fix panic in stack_map_get_build

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Date:   Thu, 10 Jan 2019 16:26:17 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Song Liu <songliubraving@...com>, netdev@...r.kernel.org
Cc:     kernel-team@...com, ast@...nel.org, naresh.kamboju@...aro.org
Subject: Re: [PATCH bpf] bpf: fix panic in stack_map_get_build_id() on i386
 and arm32

On 01/08/2019 11:20 PM, Song Liu wrote:
> As Naresh reported, test_stacktrace_build_id() causes panic on i386 and
> arm32 systems. This is caused by page_address() returns NULL in certain
> cases.
> 
> This patch fixes this error by using kmap_atomic/kunmap_atomic instead
> of page_address.
> 
> Fixes: 615755a77b24 (" bpf: extend stackmap to save binary_build_id+offset instead of address")
> Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
> Signed-off-by: Song Liu <songliubraving@...com>

Looks correct to me, and in this case as per API the assumption is allowed
that k[un]map_atomic() won't fail. I've applied it to bpf, if Naresh still
replies with a Tested-by in time, I'll add it as well to the commit.