Bug #220387 - 6.16.0 CFI panic at boot in crypto/zstd.c

Bug #220387 - 6.16.0 CFI panic at boot in crypto/zstd.c

[Fabio Scaccabarozzi]

Hello,

I reported the bug in subject on the kernel bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=220387

Kernel 6.16.0 crashes with a CFI panic at boot in crypto/zstd.c (am compiling with Clang+thinLTO).
I bisected, did some digging and managed to produce a working patch (I'm not sure of the correctness of it).
Can you please take a look at the bug and apply/rework the patch as you see fit?

I guess this could be added to stable in 6.16.2 then (patch still applies cleanly on 6.16.1).


Thanks,
Fabio

Re: Bug #220387 - 6.16.0 CFI panic at boot in crypto/zstd.c

[Herbert Xu]

On Sat, Aug 16, 2025 at 12:44:18PM +0100, Fabio Scaccabarozzi wrote:
> 
> I reported the bug in subject on the kernel bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=220387
> 
> Kernel 6.16.0 crashes with a CFI panic at boot in crypto/zstd.c (am compiling with Clang+thinLTO).
> I bisected, did some digging and managed to produce a working patch (I'm not sure of the correctness of it).
> Can you please take a look at the bug and apply/rework the patch as you see fit?
> 
> I guess this could be added to stable in 6.16.2 then (patch still applies cleanly on 6.16.1).

This bug is already fixed by

commit 962ddc5a7a4b04c007bba0f3e7298cda13c62efd
Author: Eric Biggers <ebiggers@kernel.org>
Date:   Tue Jul 8 17:59:54 2025 -0700

    crypto: acomp - Fix CFI failure due to type punning

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: Bug #220387 - 6.16.0 CFI panic at boot in crypto/zstd.c

[Fabio Scaccabarozzi]

I saw the patch was merged in 6.16.4, but I still have the boot panic.

I've updated the bug with new findings, please let me know if I can help debugging further.


Thank you,

On Fri, Aug 22, 2025, at 10:34, Herbert Xu wrote:
> On Sat, Aug 16, 2025 at 12:44:18PM +0100, Fabio Scaccabarozzi wrote:
> > 
> > I reported the bug in subject on the kernel bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=220387
> > 
> > Kernel 6.16.0 crashes with a CFI panic at boot in crypto/zstd.c (am compiling with Clang+thinLTO).
> > I bisected, did some digging and managed to produce a working patch (I'm not sure of the correctness of it).
> > Can you please take a look at the bug and apply/rework the patch as you see fit?
> > 
> > I guess this could be added to stable in 6.16.2 then (patch still applies cleanly on 6.16.1).
> 
> This bug is already fixed by
> 
> commit 962ddc5a7a4b04c007bba0f3e7298cda13c62efd
> Author: Eric Biggers <ebiggers@kernel.org>
> Date:   Tue Jul 8 17:59:54 2025 -0700
> 
>     crypto: acomp - Fix CFI failure due to type punning
> 
> Thanks,
> -- 
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>