Re: [PATCH 5.10 000/286] 5.10.209-rc1 review

[Guenter Roeck <linux@roeck-us.net>]

On 1/26/24 12:34, Nathan Chancellor wrote:
> On Fri, Jan 26, 2024 at 10:17:23AM -0800, Guenter Roeck wrote:
>> On 1/26/24 09:51, Greg Kroah-Hartman wrote:
>>> On Fri, Jan 26, 2024 at 08:46:42AM -0800, Guenter Roeck wrote:
>>>> On 1/22/24 15:55, Greg Kroah-Hartman wrote:
>>>>> This is the start of the stable review cycle for the 5.10.209 release.
>>>>> There are 286 patches in this series, all will be posted as a response
>>>>> to this one.  If anyone has any issues with these being applied, please
>>>>> let me know.
>>>>>
>>>>> Responses should be made by Wed, 24 Jan 2024 23:56:49 +0000.
>>>>> Anything received after that time might be too late.
>>>>>
>>>> [ ... ]
>>>>
>>>>> zhenwei pi <pizhenwei@bytedance.com>
>>>>>        virtio-crypto: implement RSA algorithm
>>>>>
>>>>
>>>> Curious: Why was this (and its subsequent fixes) backported to v5.10.y ?
>>>> It is quite beyond a bug fix. Also, unless I am really missing something,
>>>> the series (or at least this patch) was not applied to v5.15.y, so we now
>>>> have functionality in v5.10.y which is not in v5.15.y.
>>>
>>> See the commit text, it was a dependency of a later fix and documented
>>> as such.
>>>
>>> Having it in 5.10 and not 5.15 is a bit odd, I agree, so patches are
>>> gladly accepted :)
>>>
>>
>> We reverted the entire series from the merge because it results in a build
>> failure for us.
>>
>> In file included from /home/groeck/src/linux-chromeos/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c:10:
>> In file included from /home/groeck/src/linux-chromeos/include/linux/mpi.h:21:
>> In file included from /home/groeck/src/linux-chromeos/include/linux/scatterlist.h:5:
>> In file included from /home/groeck/src/linux-chromeos/include/linux/string.h:293:
>> /home/groeck/src/linux-chromeos/include/linux/fortify-string.h:512:4: error: call to __read_overflow2_field declared with 'warning' attribute: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
>>                          __read_overflow2_field(q_size_field, size);
> 
> For what it's worth, this is likely self inflicted for chromeos-5.10,
> which carries a revert of commit eaafc590053b ("fortify: Explicitly
> disable Clang support") as commit c19861d34c003 ("CHROMIUM: Revert
> "fortify: Explicitly disable Clang support""). I don't see the series
> that added proper support for clang to fortify in 5.18 that ended with
> commit 281d0c962752 ("fortify: Add Clang support") in that ChromeOS
> branch, so this seems somewhat expected.
> 

That explains that ;-). I don't mind if the patches stay in v5.10.y,
we have them reverted anyway.

The revert was a pure process issue, as you may see when looking into
commit c19861d34c003, so, yes, I agree that it is self-inflicted damage.
Still, that doesn't explain why the problem exists in 5.18+.

>> I also see that upstream (starting with 6.1) when trying to build it with clang,
>> so I guess it is one of those bug-for-bug compatibility things. I really have
>> no idea what causes it, or why we don't see the problem when building
>> chromeos-6.1 or chromeos-6.6, but (so far) only with chromeos-5.10 after
>> merging 5.10.209 into it. Making things worse, the problem isn't _always_
>> seen. Sometimes I can compile the file in 6.1.y without error, sometimes not.
>> I have no idea what triggers the problem.
> 
> Have a .config that reproduces it on upstream? I have not personally
> seen this warning in my build matrix nor has our continuous-integration
> matrix (I don't see it in the warning output at the bottom but that
> could have missed something for some reason) in 6.1:
> 

The following command sequence reproduces the problem for me with all stable
branches starting with 5.18.y (plus mainline).

rm -rf /tmp/crypto-build
mkdir /tmp/crypto-build
make -j CC=clang-15 mrproper >/dev/null 2>&1
make -j O=/tmp/crypto-build CC=clang-15 allmodconfig >/dev/null 2>&1
make -j O=/tmp/crypto-build W=1 CC=clang-15 drivers/crypto/virtio/virtio_crypto_akcipher_algs.o

I tried clang versions 14, 15, and 16. This is with my home system running
Ubuntu 22.04, no ChromeOS or Google specifics/internals involved. For clang-15,
the version is

Ubuntu clang version 15.0.7
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

Guenter