[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1475172392.2027.12.camel@perches.com>
Date: Thu, 29 Sep 2016 11:06:32 -0700
From: Joe Perches <joe@...ches.com>
To: Colin King <colin.king@...onical.com>,
Linus Walleij <linus.walleij@...aro.org>,
Dan Williams <dan.j.williams@...el.com>,
Vinod Koul <vinod.koul@...el.com>,
linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: coh901318: fix integer overflow when
shifting more than 32 places
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.
Powered by blists - more mailing lists