* [PATCH] video: fbdev: vermilion: use 64-bit arithmetic instead of 32-bit
@ 2018-02-07 0:04 ` Gustavo A. R. Silva
2018-03-12 15:58 ` Bartlomiej Zolnierkiewicz
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2018-02-07 0:04 UTC (permalink / raw)
To: Bartlomiej Zolnierkiewicz
Cc: dri-devel, linux-fbdev, linux-kernel, Gustavo A. R. Silva
Cast _pitch_ to u64 in order to give the compiler complete information
about the proper arithmetic to use. Notice that this variable is
being used in a context that expects an expression of type u64
(64 bits, unsigned).
The expression pitch * var->yres_virtual is currently being evaluated
using 32-bit arithmetic and the result of the operation is being stored
into variable mem, which is a variable of type u64. Based on that,
chances are there is a potential integer overflow as a result of the
operation.
Addresses-Coverity-ID: 200655 ("Unintentional integer overflow")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/video/fbdev/vermilion/vermilion.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/vermilion/vermilion.c b/drivers/video/fbdev/vermilion/vermilion.c
index 6f8d444..5172fa5 100644
--- a/drivers/video/fbdev/vermilion/vermilion.c
+++ b/drivers/video/fbdev/vermilion/vermilion.c
@@ -651,7 +651,7 @@ static int vmlfb_check_var_locked(struct fb_var_screeninfo *var,
}
pitch = ALIGN((var->xres * var->bits_per_pixel) >> 3, 0x40);
- mem = pitch * var->yres_virtual;
+ mem = (u64)pitch * var->yres_virtual;
if (mem > vinfo->vram_contig_size) {
return -ENOMEM;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] video: fbdev: vermilion: use 64-bit arithmetic instead of 32-bit
2018-02-07 0:04 ` [PATCH] video: fbdev: vermilion: use 64-bit arithmetic instead of 32-bit Gustavo A. R. Silva
@ 2018-03-12 15:58 ` Bartlomiej Zolnierkiewicz
0 siblings, 0 replies; 2+ messages in thread
From: Bartlomiej Zolnierkiewicz @ 2018-03-12 15:58 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: dri-devel, linux-fbdev, linux-kernel, Gustavo A. R. Silva
On Tuesday, February 06, 2018 06:04:24 PM Gustavo A. R. Silva wrote:
> Cast _pitch_ to u64 in order to give the compiler complete information
> about the proper arithmetic to use. Notice that this variable is
> being used in a context that expects an expression of type u64
> (64 bits, unsigned).
>
> The expression pitch * var->yres_virtual is currently being evaluated
> using 32-bit arithmetic and the result of the operation is being stored
> into variable mem, which is a variable of type u64. Based on that,
> chances are there is a potential integer overflow as a result of the
> operation.
>
> Addresses-Coverity-ID: 200655 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Patch queued for 4.17, thanks.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
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2018-02-07 0:04 ` [PATCH] video: fbdev: vermilion: use 64-bit arithmetic instead of 32-bit Gustavo A. R. Silva
2018-03-12 15:58 ` Bartlomiej Zolnierkiewicz
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