[tip: timers/urgent] posix-timers: Accept NULL clock_getres() output in stubs

[tip-bot2 for Hungyu Lin]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     5b819071e4346256c4edbae5cc2095dff25694fc
Gitweb:        https://git.kernel.org/tip/5b819071e4346256c4edbae5cc2095dff25694fc
Author:        Hungyu Lin <dennylin0707@xxxxxxxxx>
AuthorDate:    Tue, 20 Oct 2026 16:11:21 
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Sun, 25 Oct 2026 22:43:19 +01:00

posix-timers: Accept NULL clock_getres() output in stubs

With CONFIG_POSIX_TIMERS disabled, clock_getres() returns -EFAULT for a
supported clock when the result pointer is NULL. POSIX permits a NULL
result pointer to suppress returning the clock resolution.

Only copy the result when a destination is provided, in both the native
and time32 stubs. This matches the full POSIX timer implementation and
preserves clock ID validation.

Fixes: baa73d9e478f ("posix-timers: Make them configurable")
Fixes: d822cdcce43f ("posix-timers: Move compat versions of clock_gettime/settime/getres")
Signed-off-by: Hungyu Lin <dennylin0707@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://patch.msgid.link/20261020161121.85042-1-dennylin0707@xxxxxxxxx
---
 kernel/time/posix-stubs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 9b6fcb8..5a27335 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -83,7 +83,7 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, struct __kernel_time
 	case CLOCK_REALTIME:
 	case CLOCK_MONOTONIC:
 	case CLOCK_BOOTTIME:
-		if (put_timespec64(&rtn_tp, tp))
+		if (tp && put_timespec64(&rtn_tp, tp))
 			return -EFAULT;
 		return 0;
 	default:
@@ -166,7 +166,7 @@ SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
 	case CLOCK_REALTIME:
 	case CLOCK_MONOTONIC:
 	case CLOCK_BOOTTIME:
-		if (put_old_timespec32(&rtn_tp, tp))
+		if (tp && put_old_timespec32(&rtn_tp, tp))
 			return -EFAULT;
 		return 0;
 	default: