Stable backport request: skbuff: Proactively round up to kmalloc bucket size

[Daniel Díaz]

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.

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

commit 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232
Author: Kees Cook <keescook@xxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
    Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
    Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
    Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
    Cc: netdev@xxxxxxxxxxxxxxx
    Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
    Cc: David Rientjes <rientjes@xxxxxxxxxx>
    Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
    Link: https://patchwork.kernel.org/project/netdevbpf/patch/20221021234713.you.031-kees@xxxxxxxxxx/
    Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221025223811.up.360-kees@xxxxxxxxxx
    Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>


Thanks and greetings!

Daniel Díaz
daniel.diaz@xxxxxxxxxx