Hi!
> From: Igor Matheus Andrade Torrente <igormtorrente@xxxxxxxxx>
>
> commit dc13cac4862cc68ec74348a80b6942532b7735fa upstream.
>
> The return of ioremap if not checked, and can lead to a NULL to be
> assigned to hga_vram. Potentially leading to a NULL pointer
> dereference.
>
> The fix adds code to deal with this case in the error label and
> changes how the hgafb_probe handles the return of hga_card_detect.
This will break hgafb completely, right? And crash system without hga
card as a bonus.
> +++ b/drivers/video/fbdev/hgafb.c
> @@ -285,6 +285,8 @@ static int hga_card_detect(void)
> hga_vram_len = 0x08000;
>
> hga_vram = ioremap(0xb0000, hga_vram_len);
> + if (!hga_vram)
> + return -ENOMEM;
>
> if (request_region(0x3b0, 12, "hgafb"))
> release_io_ports = 1;
> @@ -344,13 +346,18 @@ static int hga_card_detect(void)
> hga_type_name = "Hercules";
> break;
> }
> - return 1;
> + return 0;
Ok, so calling convention is now "0 means detected".
> @@ -548,13 +555,11 @@ static struct fb_ops hgafb_ops = {
> static int hgafb_probe(struct platform_device *pdev)
> {
> struct fb_info *info;
> + int ret;
...
> + ret = hga_card_detect();
> + if (!ret)
> + return ret;
>
> printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
> hga_type_name, hga_vram_len/1024);
>
If the card is detected, 0 is returned, !0 is true, and we abort
detection....
Pavel
Signed-off-by: Pavel Machek <pavel@xxxxxxx>
diff --git a/drivers/video/fbdev/hgafb.c b/drivers/video/fbdev/hgafb.c
index c35f217db53f..d6a95ea49c64 100644
--- a/drivers/video/fbdev/hgafb.c
+++ b/drivers/video/fbdev/hgafb.c
@@ -282,7 +282,7 @@ static int hga_card_detect(void)
void __iomem *p, *q;
unsigned short p_save, q_save;
- hga_vram_len = 0x08000;
+ hga_vram_len = 0x08000;
hga_vram = ioremap(0xb0000, hga_vram_len);
if (!hga_vram)
@@ -558,7 +558,7 @@ static int hgafb_probe(struct platform_device *pdev)
int ret;
ret = hga_card_detect();
- if (!ret)
+ if (ret)
return ret;
printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
--
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