linux-kernel - [tip:timers/urgent] lib/vdso/32: Remove inconsistent NULL pointer checks

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Message-ID: <tip-a9446a906f52292c52ecbd5be78eaa4d8395756c@git.kernel.org>
Date:   Tue, 30 Jul 2019 15:19:09 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     luto@...nel.org, linux-kernel@...r.kernel.org,
        vincenzo.frascino@....com, tglx@...utronix.de, mingo@...nel.org,
        hpa@...or.com
Subject: [tip:timers/urgent] lib/vdso/32: Remove inconsistent NULL pointer
 checks

Commit-ID:  a9446a906f52292c52ecbd5be78eaa4d8395756c
Gitweb:     https://git.kernel.org/tip/a9446a906f52292c52ecbd5be78eaa4d8395756c
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 28 Jul 2019 15:12:52 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 31 Jul 2019 00:09:09 +0200

lib/vdso/32: Remove inconsistent NULL pointer checks

The 32bit variants of vdso_clock_gettime()/getres() have a NULL pointer
check for the timespec pointer. That's inconsistent vs. 64bit.

But the vdso implementation will never be consistent versus the syscall
because the only case which it can handle is NULL. Any other invalid
pointer will cause a segfault. So special casing NULL is not really useful.

Remove it along with the superflouos syscall fallback invocation as that
will return -EFAULT anyway. That also gets rid of the dubious typecast
which only works because the pointer is NULL.

Fixes: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation")
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@....com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@....com>
Reviewed-by: Andy Lutomirski <luto@...nel.org>
Link: https://lkml.kernel.org/r/20190728131648.587523358@linutronix.de

---
 lib/vdso/gettimeofday.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 2d1c1f241fd9..e28f5a607a5f 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -115,9 +115,6 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 	struct __kernel_timespec ts;
 	int ret;
 
-	if (res == NULL)
-		goto fallback;
-
 	ret = __cvdso_clock_gettime(clock, &ts);
 
 	if (ret == 0) {
@@ -126,9 +123,6 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 	}
 
 	return ret;
-
-fallback:
-	return clock_gettime_fallback(clock, (struct __kernel_timespec *)res);
 }
 
 static __maybe_unused int
@@ -204,10 +198,8 @@ int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 		goto fallback;
 	}
 
-	if (res) {
-		res->tv_sec = 0;
-		res->tv_nsec = ns;
-	}
+	res->tv_sec = 0;
+	res->tv_nsec = ns;
 
 	return 0;
 
@@ -221,9 +213,6 @@ __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
 	struct __kernel_timespec ts;
 	int ret;
 
-	if (res == NULL)
-		goto fallback;
-
 	ret = __cvdso_clock_getres(clock, &ts);
 
 	if (ret == 0) {
@@ -232,8 +221,5 @@ __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
 	}
 
 	return ret;
-
-fallback:
-	return clock_getres_fallback(clock, (struct __kernel_timespec *)res);
 }
 #endif /* VDSO_HAS_CLOCK_GETRES */