From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Prabhakar <prabhakar.csengg@gmail.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Magnus Damm <magnus.damm@gmail.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
linux-rtc@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Biju Das <biju.das.jz@bp.renesas.com>,
Fabrizio Castro <fabrizio.castro.jz@renesas.com>,
Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Subject: Re: [PATCH 07/12] rtc: rzn1: fix alarm range check truncation on 32-bit systems
Date: Wed, 17 Jun 2026 18:55:38 +0200 [thread overview]
Message-ID: <20260617165538dad7e36b@mail.local> (raw)
In-Reply-To: <20260615154805.1619693-8-prabhakar.mahadev-lad.rj@bp.renesas.com>
On 15/06/2026 16:48:00+0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> alarm and farest were declared as unsigned long, but
> rtc_tm_to_time64() returns time64_t (s64). On 32-bit systems where
> unsigned long is 32 bits, the assignment silently truncates the upper
> 32 bits of the timestamp.
>
> Fix by declaring alarm and farest as time64_t and replacing
> time_after() with a direct signed comparison, which is correct for
> time64_t values that will never realistically overflow.
>
I'd argue that this is never going to overflow ever as unsigned long
gets you to 2106 which is way past the usable range of the RTC so there
is a trade off between the size you are going to take on the stack and
the actual usefulness of the fix.
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2026-06-17 16:55 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-15 15:47 [PATCH 00/12] Add RTC support for Renesas RZ/T2H and RZ/N2H SoCs Prabhakar
2026-06-15 15:47 ` [PATCH 01/12] dt-bindings: rtc: renesas,rzn1-rtc: Add RZ/T2H and RZ/N2H support Prabhakar
2026-06-15 15:56 ` sashiko-bot
2026-06-15 16:22 ` Conor Dooley
2026-06-17 9:38 ` Wolfram Sang
2026-06-15 15:47 ` [PATCH 02/12] rtc: rzn1: Handle EPROBE_DEFER for optional pps interrupt Prabhakar
2026-06-15 15:58 ` sashiko-bot
2026-06-17 9:55 ` Wolfram Sang
2026-06-15 15:47 ` [PATCH 03/12] rtc: rzn1: Fix malformed MODULE_AUTHOR string Prabhakar
2026-06-17 7:19 ` Geert Uytterhoeven
2026-06-17 9:55 ` Wolfram Sang
2026-06-15 15:47 ` [PATCH 04/12] rtc: Kconfig: Broaden RTC_DRV_RZN1 dependency to ARCH_RENESAS Prabhakar
2026-06-17 9:57 ` Wolfram Sang
2026-06-15 15:47 ` [PATCH 05/12] rtc: rzn1: Add system suspend/resume support and wakeup capability Prabhakar
2026-06-15 15:59 ` sashiko-bot
2026-06-17 10:02 ` Wolfram Sang
2026-06-15 15:47 ` [PATCH 06/12] rtc: rzn1: Sort headers alphabetically Prabhakar
2026-06-17 7:22 ` Geert Uytterhoeven
2026-06-17 10:04 ` Wolfram Sang
2026-06-15 15:48 ` [PATCH 07/12] rtc: rzn1: fix alarm range check truncation on 32-bit systems Prabhakar
2026-06-15 16:00 ` sashiko-bot
2026-06-17 7:29 ` Geert Uytterhoeven
2026-06-17 10:49 ` Wolfram Sang
2026-06-17 10:57 ` Wolfram Sang
2026-06-17 16:55 ` Alexandre Belloni [this message]
2026-06-15 15:48 ` [PATCH 08/12] rtc: rzn1: Dynamically calculate synchronization delay based on clock rate Prabhakar
2026-06-15 15:57 ` sashiko-bot
2026-06-17 10:58 ` Wolfram Sang
2026-06-15 15:48 ` [PATCH 09/12] rtc: rzn1: Use temporary variable for struct device Prabhakar
2026-06-15 17:56 ` sashiko-bot
2026-06-17 11:00 ` Wolfram Sang
2026-06-17 11:08 ` Wolfram Sang
2026-06-15 15:48 ` [PATCH 10/12] rtc: rzn1: Consistently use dev_err_probe() Prabhakar
2026-06-17 7:24 ` Geert Uytterhoeven
2026-06-17 11:01 ` Wolfram Sang
2026-06-15 15:48 ` [PATCH 11/12] rtc: rzn1: use FIELD_PREP/FIELD_GET and GENMASK for register access Prabhakar
2026-06-15 15:57 ` sashiko-bot
2026-06-17 11:06 ` Wolfram Sang
2026-06-15 15:48 ` [PATCH 12/12] rtc: rzn1: Add support for Renesas RZ/T2H and RZ/N2H SoCs Prabhakar
2026-06-15 15:58 ` sashiko-bot
2026-06-17 11:10 ` Wolfram Sang
2026-06-17 9:18 ` [PATCH 00/12] Add RTC " Wolfram Sang
2026-06-17 11:12 ` Wolfram Sang
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