[PATCH 4.14 090/323] posix-timers: Preserve return value in clock_adjtime32()

[Greg Kroah-Hartman]

From: Chen Jun <chenjun102@xxxxxxxxxx>

commit 2d036dfa5f10df9782f5278fc591d79d283c1fad upstream.

The return value on success (>= 0) is overwritten by the return value of
put_old_timex32(). That works correct in the fault case, but is wrong for
the success case where put_old_timex32() returns 0.

Just check the return value of put_old_timex32() and return -EFAULT in case
it is not zero.

[ tglx: Massage changelog ]

Fixes: 3a4d44b61625 ("ntp: Move adjtimex related compat syscalls to native counterparts")
Signed-off-by: Chen Jun <chenjun102@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210414030449.90692-1-chenjun102@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/time/posix-timers.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1172,8 +1172,8 @@ COMPAT_SYSCALL_DEFINE2(clock_adjtime, cl
 
 	err = kc->clock_adj(which_clock, &ktx);
 
-	if (err >= 0)
-		err = compat_put_timex(utp, &ktx);
+	if (err >= 0 && compat_put_timex(utp, &ktx))
+		return -EFAULT;
 
 	return err;
 }