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From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>
Cc: dri-devel@lists.freedesktop.org,
	Boris Brezillon <boris.brezillon@bootlin.com>,
	stable@vger.kernel.org
Subject: [PATCH] drm/sun4i: Fix an ulong overflow in the dotclock driver
Date: Thu, 18 Oct 2018 11:25:46 +0200	[thread overview]
Message-ID: <20181018092546.23078-1-boris.brezillon@bootlin.com> (raw)

The calculated ideal rate can easily overflow an unsigned long, thus
making the best div selection buggy as soon as no ideal match is found
before the overflow occurs.

Fixes: 4731a72df273 ("drm/sun4i: request exact rates to our parents")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/gpu/drm/sun4i/sun4i_dotclock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index e36004fbe453..82132a9bd1d5 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -81,9 +81,12 @@ static long sun4i_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
 	int i;
 
 	for (i = tcon->dclk_min_div; i <= tcon->dclk_max_div; i++) {
-		unsigned long ideal = rate * i;
+		u64 ideal = (u64)rate * i;
 		unsigned long rounded;
 
+		if (ideal > ULONG_MAX)
+			break;
+
 		rounded = clk_hw_round_rate(clk_hw_get_parent(hw),
 					    ideal);
 
-- 
2.14.1

WARNING: multiple messages have this Message-ID (diff)
From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>
Cc: Boris Brezillon <boris.brezillon@bootlin.com>,
	stable@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: [PATCH] drm/sun4i: Fix an ulong overflow in the dotclock driver
Date: Thu, 18 Oct 2018 11:25:46 +0200	[thread overview]
Message-ID: <20181018092546.23078-1-boris.brezillon@bootlin.com> (raw)

The calculated ideal rate can easily overflow an unsigned long, thus
making the best div selection buggy as soon as no ideal match is found
before the overflow occurs.

Fixes: 4731a72df273 ("drm/sun4i: request exact rates to our parents")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/gpu/drm/sun4i/sun4i_dotclock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index e36004fbe453..82132a9bd1d5 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -81,9 +81,12 @@ static long sun4i_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
 	int i;
 
 	for (i = tcon->dclk_min_div; i <= tcon->dclk_max_div; i++) {
-		unsigned long ideal = rate * i;
+		u64 ideal = (u64)rate * i;
 		unsigned long rounded;
 
+		if (ideal > ULONG_MAX)
+			break;
+
 		rounded = clk_hw_round_rate(clk_hw_get_parent(hw),
 					    ideal);
 
-- 
2.14.1

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             reply	other threads:[~2018-10-18 17:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-18  9:25 Boris Brezillon [this message]
2018-10-18  9:25 ` [PATCH] drm/sun4i: Fix an ulong overflow in the dotclock driver Boris Brezillon
2018-10-18  9:49 ` Maxime Ripard
2018-10-18  9:49   ` Maxime Ripard

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