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From: Wake Liu <wakel@google.com>
To: Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	 Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: linux-kernel@vger.kernel.org, wakel@google.com
Subject: [PATCH] vdso: Define NSEC_PER_SEC as 64-bit to prevent overflow
Date: Wed,  6 Aug 2025 00:21:53 +0800	[thread overview]
Message-ID: <20250805162153.952693-1-wakel@google.com> (raw)

The constant NSEC_PER_SEC (1,000,000,000) is defined as a long literal.
On 32-bit systems like arm32, where long is 32 bits, this value can
overflow when used in 64-bit calculations.

This can lead to incorrect time calculations within the VDSO.

To fix this, define NSEC_PER_SEC as a long long literal (1000000000LL),
ensuring it is treated as a 64-bit value on all architectures and
preventing potential overflows.

Signed-off-by: Wake Liu <wakel@google.com>
---
 include/vdso/time64.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/vdso/time64.h b/include/vdso/time64.h
index b40cfa2aa33c..07641b27d139 100644
--- a/include/vdso/time64.h
+++ b/include/vdso/time64.h
@@ -8,7 +8,7 @@
 #define NSEC_PER_USEC	1000L
 #define NSEC_PER_MSEC	1000000L
 #define USEC_PER_SEC	1000000L
-#define NSEC_PER_SEC	1000000000L
+#define NSEC_PER_SEC	1000000000LL
 #define PSEC_PER_SEC	1000000000000LL
 #define FSEC_PER_SEC	1000000000000000LL
 
-- 
2.50.1.565.gc32cd1483b-goog


             reply	other threads:[~2025-08-05 16:21 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-05 16:21 Wake Liu [this message]
2025-08-06  8:44 ` Thomas Gleixner
2025-08-06  8:55 ` Thomas Gleixner
2025-08-09  9:49   ` Wake Liu
2025-08-10  8:03     ` Thomas Gleixner
2025-08-10  8:28       ` Thomas Weißschuh
2025-09-15 19:19         ` [PATCH v2] selftests/timers: Consolidate and fix 32-bit overflow in timespec_sub Wake Liu
2025-09-21  7:49           ` Thomas Gleixner
2026-01-07 23:19             ` Carlos Llamas
2025-08-06 20:28 ` [PATCH] vdso: Define NSEC_PER_SEC as 64-bit to prevent overflow kernel test robot
2025-08-07  7:37 ` kernel test robot
  -- strict thread matches above, loose matches on Subject: below --
2025-08-05 16:20 Wake Liu

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