[PATCH 1/2] copy_process: Handle architectures where sizeof(unsigned long) < sizeof(u64)

[Simon Schuster via B4 Relay]

From: Simon Schuster <schuster.simon@xxxxxxxxxxxxxxxxxx>

With the introduction of clone3 in commit 7f192e3cd316 ("fork: add
clone3") the effective bit width of clone_flags on all architectures was
increased from 32bit to 64bit. However, the signature of the copy_*
helper functions (e.g., copy_sighand) used by copy_process was not
adapted, as such, they potentially truncate the flags on architectures
such as nios2, where unsigned long is a 32bit unsigned integer type.

This can, for instance, be observed via failures of kernel selftest
clone3_clear_sighand, which attempts to trigger the conditional

	if (clone_flags & CLONE_CLEAR_SIGHAND)

in function copy_sighand within fork.c that 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 via their
declared u64 type, invariant of architecture-dependent integer sizes.

Signed-off-by: Simon Schuster <schuster.simon@xxxxxxxxxxxxxxxxxx>
---
 kernel/fork.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 5115be549234..0e9b2dd6c365 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1510,7 +1510,7 @@ static struct mm_struct *dup_mm(struct task_struct *tsk,
 	return NULL;
 }
 
-static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
+static int copy_mm(u64 clone_flags, struct task_struct *tsk)
 {
 	struct mm_struct *mm, *oldmm;
 
@@ -1548,7 +1548,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
 	return 0;
 }
 
-static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
+static int copy_fs(u64 clone_flags, struct task_struct *tsk)
 {
 	struct fs_struct *fs = current->fs;
 	if (clone_flags & CLONE_FS) {
@@ -1569,7 +1569,7 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
 	return 0;
 }
 
-static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
+static int copy_files(u64 clone_flags, struct task_struct *tsk,
 		      int no_files)
 {
 	struct files_struct *oldf, *newf;
@@ -1599,7 +1599,7 @@ 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;
 
@@ -1648,7 +1648,7 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
 	posix_cputimers_group_init(pct, cpu_limit);
 }
 
-static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
+static int copy_signal(u64 clone_flags, struct task_struct *tsk)
 {
 	struct signal_struct *sig;
 

-- 
2.39.5