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SubjectRe: Stable backport request: skbuff: Proactively round up to kmalloc bucket size
On Mon, May 22, 2023 at 12:23:50PM -0600, Daniel Díaz wrote:
> Hello!
>
> Would the stable maintainers please consider backporting the following
> commit to the 6.1? We are trying to build gki_defconfig (plus a few
> extras) on Arm64 and test it under Qemu-arm64, but it fails to boot.
> Bisection has pointed here.

I do not see a "gki_defconfig" in the kernel tree, is this just
out-of-tree stuff?

If so, why not just add this to your out-of-tree stuff?

> We have verified that cherry-picking this patch on top of v6.1.29
> applies cleanly and allows the kernel to boot.

So what is breaking that requires this to fix the problem? What is the
problem?

>
> commit 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232
> Author: Kees Cook <keescook@chromium.org>
> Date: Tue Oct 25 15:39:35 2022 -0700
>
> skbuff: Proactively round up to kmalloc bucket size
>
> Instead of discovering the kmalloc bucket size _after_ allocation, round
> up proactively so the allocation is explicitly made for the full size,
> allowing the compiler to correctly reason about the resulting size of
> the buffer through the existing __alloc_size() hint.
>
> This will allow for kernels built with CONFIG_UBSAN_BOUNDS or the
> coming dynamic bounds checking under CONFIG_FORTIFY_SOURCE to gain
> back the __alloc_size() hints that were temporarily reverted in commit
> 93dd04ab0b2b ("slab: remove __alloc_size attribute from
> __kmalloc_track_caller")
>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: David Rientjes <rientjes@google.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Link: https://patchwork.kernel.org/project/netdevbpf/patch/20221021234713.you.031-kees@kernel.org/
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Link: https://lore.kernel.org/r/20221025223811.up.360-kees@kernel.org
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

This feels like a new feature, why would a 6.1.y system need it? What
commit id does it fix?

thanks,

greg k-h

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