Re: [PATCH v2 1/4] copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64)

Re: [PATCH v2 1/4] copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64)

[David Hildenbrand]

On 01.09.25 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@siemens-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@vger.kernel.org # linux-5.5+
> Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---

(stripping To list)

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

-- 
Cheers

David / dhildenb

Re: [PATCH v2 2/4] copy_process: pass clone_flags as u64 across calltree

[David Hildenbrand]

On 01.09.25 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@siemens-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, with a new type of u64 for the flags.
> However, for most consumers of clone_flags the interface was not
> changed from the previous type of unsigned long.
> 
> While this works fine as long as none of the new 64-bit flag bits
> (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
> undesirable in terms of the principle of least surprise.
> 
> Thus, this commit fixes all relevant interfaces of callees to
> sys_clone3/copy_process (excluding the architecture-specific
> copy_thread) to consistently pass clone_flags as u64, so that
> no truncation to 32-bit integers occurs on 32-bit architectures.
> 
> Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
>   block/blk-ioc.c                | 2 +-
>   fs/namespace.c                 | 2 +-
>   include/linux/cgroup.h         | 4 ++--
>   include/linux/cred.h           | 2 +-
>   include/linux/iocontext.h      | 6 +++---
>   include/linux/ipc_namespace.h  | 4 ++--
>   include/linux/lsm_hook_defs.h  | 2 +-
>   include/linux/mnt_namespace.h  | 2 +-
>   include/linux/nsproxy.h        | 2 +-
>   include/linux/pid_namespace.h  | 4 ++--
>   include/linux/rseq.h           | 4 ++--
>   include/linux/sched/task.h     | 2 +-
>   include/linux/security.h       | 4 ++--
>   include/linux/sem.h            | 4 ++--
>   include/linux/time_namespace.h | 4 ++--
>   include/linux/uprobes.h        | 4 ++--
>   include/linux/user_events.h    | 4 ++--
>   include/linux/utsname.h        | 4 ++--
>   include/net/net_namespace.h    | 4 ++--
>   include/trace/events/task.h    | 6 +++---
>   ipc/namespace.c                | 2 +-
>   ipc/sem.c                      | 2 +-
>   kernel/cgroup/namespace.c      | 2 +-
>   kernel/cred.c                  | 2 +-
>   kernel/events/uprobes.c        | 2 +-
>   kernel/fork.c                  | 8 ++++----
>   kernel/nsproxy.c               | 4 ++--
>   kernel/pid_namespace.c         | 2 +-
>   kernel/sched/core.c            | 4 ++--
>   kernel/sched/fair.c            | 2 +-
>   kernel/sched/sched.h           | 4 ++--
>   kernel/time/namespace.c        | 2 +-
>   kernel/utsname.c               | 2 +-
>   net/core/net_namespace.c       | 2 +-
>   security/apparmor/lsm.c        | 2 +-
>   security/security.c            | 2 +-
>   security/selinux/hooks.c       | 2 +-
>   security/tomoyo/tomoyo.c       | 2 +-
>   38 files changed, 59 insertions(+), 59 deletions(-)
> 
> diff --git a/block/blk-ioc.c b/block/blk-ioc.c
> index 9fda3906e5f5..d15918d7fabb 100644
> --- a/block/blk-ioc.c

(adjust To: list)

Hopefully we caught most of them. The ones not called "clone_flags" are 
a bit nasty.

We could have split of some changes (e.g., trace event), but likely not 
worth  it.

Thanks!

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

-- 
Cheers

David / dhildenb

Re: [PATCH v2 3/4] arch: copy_thread: pass clone_flags as u64

[David Hildenbrand]

On 01.09.25 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@siemens-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, with a new type of u64 for the flags.
> However, for most consumers of clone_flags the interface was not
> changed from the previous type of unsigned long.
> 
> While this works fine as long as none of the new 64-bit flag bits
> (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
> undesirable in terms of the principle of least surprise.
> 
> Thus, this commit fixes all relevant interfaces of the copy_thread
> function that is called from copy_process to consistently pass
> clone_flags as u64, so that no truncation to 32-bit integers occurs on
> 32-bit architectures.
> 
> Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
> ---
>   arch/alpha/kernel/process.c      | 2 +-
>   arch/arc/kernel/process.c        | 2 +-
>   arch/arm/kernel/process.c        | 2 +-
>   arch/arm64/kernel/process.c      | 2 +-
>   arch/csky/kernel/process.c       | 2 +-
>   arch/hexagon/kernel/process.c    | 2 +-
>   arch/loongarch/kernel/process.c  | 2 +-
>   arch/m68k/kernel/process.c       | 2 +-
>   arch/microblaze/kernel/process.c | 2 +-
>   arch/mips/kernel/process.c       | 2 +-
>   arch/nios2/kernel/process.c      | 2 +-
>   arch/openrisc/kernel/process.c   | 2 +-
>   arch/parisc/kernel/process.c     | 2 +-
>   arch/powerpc/kernel/process.c    | 2 +-
>   arch/riscv/kernel/process.c      | 2 +-
>   arch/s390/kernel/process.c       | 2 +-
>   arch/sh/kernel/process_32.c      | 2 +-
>   arch/sparc/kernel/process_32.c   | 2 +-
>   arch/sparc/kernel/process_64.c   | 2 +-
>   arch/um/kernel/process.c         | 2 +-
>   arch/x86/include/asm/fpu/sched.h | 2 +-
>   arch/x86/include/asm/shstk.h     | 4 ++--
>   arch/x86/kernel/fpu/core.c       | 2 +-
>   arch/x86/kernel/process.c        | 2 +-
>   arch/x86/kernel/shstk.c          | 2 +-
>   arch/xtensa/kernel/process.c     | 2 +-
>   26 files changed, 27 insertions(+), 27 deletions(-)
> 

(Adjust To: list)

Thanks!

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

-- 
Cheers

David / dhildenb

Re: [PATCH v2 3/4] arch: copy_thread: pass clone_flags as u64

[Andreas Larsson]

On 2025-09-02 09:15, John Paul Adrian Glaubitz wrote:
>> Thanks for this and for the whole series! Needed foundation for a
>> sparc32 clone3 implementation as well.
> 
> Can you implement clone3 for sparc64 as well?

(heavily pairing down the to list)

We'll take a look at that as well.

Cheers,
Andreas