linux-kernel - [tip: timers/core] clocksource/drivers/timer-ti-dm: Fix uninitialized pointer access

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Date:   Thu, 16 Jan 2020 21:31:00 -0000
From:   "tip-bot2 for Tony Lindgren" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Yangtao Li <tiny.windzz@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Olof Johansson <olof@...om.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: timers/core] clocksource/drivers/timer-ti-dm: Fix uninitialized
 pointer access

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

Commit-ID:     4341067cfc20582195f47383cf059589b2641465
Gitweb:        https://git.kernel.org/tip/4341067cfc20582195f47383cf059589b2641465
Author:        Tony Lindgren <tony@...mide.com>
AuthorDate:    Mon, 06 Jan 2020 12:37:00 -08:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Thu, 16 Jan 2020 19:09:02 +01:00

clocksource/drivers/timer-ti-dm: Fix uninitialized pointer access

Clean-up commit 8c82723414d5 ("clocksource/drivers/timer-ti-dm: Switch to
platform_get_irq") caused a regression where we now try to access
uninitialized data for timer:

drivers/clocksource/timer-ti-dm.c: In function 'omap_dm_timer_probe':
drivers/clocksource/timer-ti-dm.c:798:13: warning: 'timer' may be used
uninitialized in this function [-Wmaybe-uninitialized]

On boot we now get:

Unable to handle kernel NULL pointer dereference at virtual address
00000004
...
(omap_dm_timer_probe) from [<c061ac7c>] (platform_drv_probe+0x48/0x98)
(platform_drv_probe) from [<c0618c04>] (really_probe+0x1dc/0x348)
(really_probe) from [<c0618ef4>] (driver_probe_device+0x5c/0x160)

Let's fix the issue by moving platform_get_irq to happen after timer has
been allocated.

Fixes: bc83caddf17b ("clocksource/drivers/timer-ti-dm: Switch to platform_get_irq")
Cc: Yangtao Li <tiny.windzz@...il.com>
Signed-off-by: Tony Lindgren <tony@...mide.com>
Acked-by: Olof Johansson <olof@...om.net>
Acked-by: Yangtao Li <tiny.windzz@...il.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Link: https://lore.kernel.org/r/20200106203700.21009-1-tony@atomide.com
---
 drivers/clocksource/timer-ti-dm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
index bd16efb..269a994 100644
--- a/drivers/clocksource/timer-ti-dm.c
+++ b/drivers/clocksource/timer-ti-dm.c
@@ -795,14 +795,14 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	timer->irq = platform_get_irq(pdev, 0);
-	if (timer->irq < 0)
-		return timer->irq;
-
 	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 	if (!timer)
 		return  -ENOMEM;
 
+	timer->irq = platform_get_irq(pdev, 0);
+	if (timer->irq < 0)
+		return timer->irq;
+
 	timer->fclk = ERR_PTR(-ENODEV);
 	timer->io_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(timer->io_base))