5.15-stable review patch. If anyone has any objections, please let me know.
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From: Simon Schuster schuster.simon@siemens-energy.com
commit 04ff48239f46e8b493571e260bd0e6c3a6400371 upstream.
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 Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-1-53fcf5577d57@si... Acked-by: David Hildenbrand david@redhat.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/fork.c +++ b/kernel/fork.c @@ -1595,7 +1595,7 @@ static int copy_io(unsigned long clone_f 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;