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Date:   Wed, 24 May 2023 06:51:52 -0700
From:   Kees Cook <kees@kernel.org>
To:     =?ISO-8859-1?Q?Daniel_D=EDaz?= <daniel.diaz@linaro.org>,
        Vlastimil Babka <vbabka@suse.cz>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <sashal@kernel.org>,
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        open list <linux-kernel@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
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        Sumit Semwal <sumit.semwal@linaro.org>
Subject: =?US-ASCII?Q?Re=3A_Stable_backport_request=3A_skbuff=3A_Pro?= =?US-ASCII?Q?actively_round_up_to_kmalloc_bucket_size?=
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On May 23, 2023 8:52:53 PM PDT, "Daniel D=C3=ADaz" <daniel=2Ediaz@linaro=2E=
org> wrote:
>Hello!
>
>On Tue, 23 May 2023 at 00:28, Vlastimil Babka <vbabka@suse=2Ecz> wrote:
>> On 5/22/23 20:23, Daniel D=C3=ADaz wrote:
>> > Hello!
>> >
>> > Would the stable maintainers please consider backporting the followin=
g
>> > commit to the 6=2E1? We are trying to build gki_defconfig (plus a few
>> > extras) on Arm64 and test it under Qemu-arm64, but it fails to boot=
=2E
>> > Bisection has pointed here=2E
>>
>> You mean the bisection was done to find the first "good" commit between=
 6=2E1
>> and e=2Eg=2E 6=2E3?
>>
>> As others said, this commit wasn't expected to be a fix to a known bug=
=2E
>> Maybe you found one that we didn't know of, or it might be accidentaly
>> masking some other bug=2E
>
>How interesting! Yes, we happened to run a bisection between v6=2E1 and
>v6=2E3 and we found where it started working with the following
>configuration:
>  https://storage=2Etuxsuite=2Ecom/public/linaro/daniel/builds/2QA2CHQUpq=
Ke27FyMZrBNILVwXi/config

Ah yes, from CONFIG_UBSAN_BOUNDS=3Dy and CONFIG_UBSAN_TRAP=3Dy

This was a known issue in upstream, oddly only exposed on arm64=2E Somethi=
ng re-broke with __alloc_size after commit 93dd04ab0b2b had tried to work a=
round it=2E I didn't think any kernel released with this broken, though, so=
 perhaps what broke it got added to -stable?

>With that patch on top of v6=2E1=2E29 it boots fine under Qemu-arm64; as
>v6=2E1=2Ey stands, it panics with this:

It should be fine to backport the patch, IMO=2E


--=20
Kees Cook