From: joe@perches.com (Joe Perches)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] dmaengine: coh901318: fix integer overflow when shifting more than 32 places
Date: Thu, 29 Sep 2016 11:06:32 -0700 [thread overview]
Message-ID: <1475172392.2027.12.camel@perches.com> (raw)
In-Reply-To: <20160929175725.14157-1-colin.king@canonical.com>
On Thu, 2016-09-29 at 18:57 +0100, Colin King wrote:
> Currently U300_DMA_CHANNELS is set to 40, meaning that the shift of 1 can
> be more than 32 places, which leads to a 32 bit integer overflow. Fix this
> by casting 1 to a u64 (the same type as started_channels) before shifting
> it.
trivia:
> diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
[]
> @@ -1353,7 +1353,7 @@ static ssize_t coh901318_debugfs_read(struct file *file, char __user *buf,
> ? tmp += sprintf(tmp, "DMA -- enabled dma channels\n");
> ?
> ? for (i = 0; i < U300_DMA_CHANNELS; i++)
> - if (started_channels & (1 << i))
> + if (started_channels & ((u64)1 << i))
Using
if (started_channels & (1ULL << i))
would be more common.
It's also how started_channel bits are set and cleared later in the file.
And maybe the for loop should use braces.
WARNING: multiple messages have this Message-ID (diff)
From: Joe Perches <joe@perches.com>
To: Colin King <colin.king@canonical.com>,
Linus Walleij <linus.walleij@linaro.org>,
Dan Williams <dan.j.williams@intel.com>,
Vinod Koul <vinod.koul@intel.com>,
linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dmaengine: coh901318: fix integer overflow when shifting more than 32 places
Date: Thu, 29 Sep 2016 11:06:32 -0700 [thread overview]
Message-ID: <1475172392.2027.12.camel@perches.com> (raw)
In-Reply-To: <20160929175725.14157-1-colin.king@canonical.com>
On Thu, 2016-09-29 at 18:57 +0100, Colin King wrote:
> Currently U300_DMA_CHANNELS is set to 40, meaning that the shift of 1 can
> be more than 32 places, which leads to a 32 bit integer overflow. Fix this
> by casting 1 to a u64 (the same type as started_channels) before shifting
> it.
trivia:
> diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
[]
> @@ -1353,7 +1353,7 @@ static ssize_t coh901318_debugfs_read(struct file *file, char __user *buf,
> tmp += sprintf(tmp, "DMA -- enabled dma channels\n");
>
> for (i = 0; i < U300_DMA_CHANNELS; i++)
> - if (started_channels & (1 << i))
> + if (started_channels & ((u64)1 << i))
Using
if (started_channels & (1ULL << i))
would be more common.
It's also how started_channel bits are set and cleared later in the file.
And maybe the for loop should use braces.
next prev parent reply other threads:[~2016-09-29 18:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-29 17:57 [PATCH] dmaengine: coh901318: fix integer overflow when shifting more than 32 places Colin King
2016-09-29 17:57 ` Colin King
2016-09-29 18:06 ` Joe Perches [this message]
2016-09-29 18:06 ` Joe Perches
2016-10-04 12:23 ` Linus Walleij
2016-10-04 12:23 ` Linus Walleij
2016-10-04 15:36 ` Vinod Koul
2016-10-04 15:36 ` Vinod Koul
2016-10-04 16:01 ` Joe Perches
2016-10-04 16:01 ` Joe Perches
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