netdev - Re: [PATCH v2 1/4] copy_sighand: Handle architectures where sizeof(unsigned long)

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Message-ID: <94ec640b-76cd-478e-9ee7-ff8597d1fafc@redhat.com>
Date: Mon, 1 Sep 2025 15:24:59 +0200
From: David Hildenbrand <david@...hat.com>
To: schuster.simon@...mens-energy.com, Dinh Nguyen <dinguyen@...nel.org>,
 Christian Brauner <brauner@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
 <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-csky@...r.kernel.org,
 linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 cgroups@...r.kernel.org, linux-security-module@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, netdev@...r.kernel.org,
 linux-perf-users@...r.kernel.org, apparmor@...ts.ubuntu.com,
 selinux@...r.kernel.org, linux-alpha@...r.kernel.org,
 linux-snps-arc@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-hexagon@...r.kernel.org, loongarch@...ts.linux.dev,
 linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
 linux-openrisc@...r.kernel.org, linux-parisc@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
 linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
 linux-um@...ts.infradead.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/4] copy_sighand: Handle architectures where
 sizeof(unsigned long) < sizeof(u64)

On 01.09.25 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@...mens-energy.com>
> 
> With the introduction of clone3 in commit 7f192e3cd316 ("fork: add
> clone3") the effective bit width of clone_flags on all architectures was
> increased from 32-bit to 64-bit. However, the signature of the copy_*
> helper functions (e.g., copy_sighand) used by copy_process was not
> adapted.
> 
> As such, they truncate the flags on any 32-bit architectures that
> supports clone3 (arc, arm, csky, m68k, microblaze, mips32, openrisc,
> parisc32, powerpc32, riscv32, x86-32 and xtensa).
> 
> For copy_sighand with CLONE_CLEAR_SIGHAND being an actual u64
> constant, this triggers an observable bug in kernel selftest
> clone3_clear_sighand:
> 
>          if (clone_flags & CLONE_CLEAR_SIGHAND)
> 
> in function copy_sighand within fork.c will always fail given:
> 
>          unsigned long /* == uint32_t */ clone_flags
>          #define CLONE_CLEAR_SIGHAND 0x100000000ULL
> 
> This commit fixes the bug by always passing clone_flags to copy_sighand
> via their declared u64 type, invariant of architecture-dependent integer
> sizes.
> 
> Fixes: b612e5df4587 ("clone3: add CLONE_CLEAR_SIGHAND")
> Cc: stable@...r.kernel.org # linux-5.5+
> Signed-off-by: Simon Schuster <schuster.simon@...mens-energy.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---

(stripping To list)

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb