From: Simon Schuster Date: Mon, 1 Sep 2025 13:09:50 +0000 (+0200) Subject: copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64) X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=04ff48239f46e8b493571e260bd0e6c3a6400371;p=users%2Fhch%2Fmisc.git copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64) 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 Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-1-53fcf5577d57@siemens-energy.com Acked-by: David Hildenbrand Reviewed-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner --- diff --git a/kernel/fork.c b/kernel/fork.c index af673856499d..4e2c5a3e8989 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1596,7 +1596,7 @@ static int copy_files(unsigned long clone_flags, struct task_struct *tsk, return 0; } -static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) +static int copy_sighand(u64 clone_flags, struct task_struct *tsk) { struct sighand_struct *sig;