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video: hgafb: fix potential NULL pointer dereference

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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.

Cc: Ferenc Bakonyi <fero@drama.obuda.kando.hu>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
Link: https://lore.kernel.org/r/20210503115736.2104747-40-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Igor Matheus Andrade Torrente 2021-05-03 13:57:06 +02:00 • committed by Greg Kroah-Hartman
parent 58c0cc2d90
commit dc13cac486
1 changed files with 13 additions and 8 deletions
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21
drivers/video/fbdev/hgafb.c
View file

@ -285,6 +285,8 @@ static int hga_card_detect(void)
hga_vram_len = 0x08000; hga_vram_len = 0x08000;
hga_vram = ioremap(0xb0000, hga_vram_len); hga_vram = ioremap(0xb0000, hga_vram_len);
if (!hga_vram)
return -ENOMEM;
if (request_region(0x3b0, 12, "hgafb")) if (request_region(0x3b0, 12, "hgafb"))
release_io_ports = 1; release_io_ports = 1;
@ -344,13 +346,18 @@ static int hga_card_detect(void)
hga_type_name = "Hercules"; hga_type_name = "Hercules";
break; break;
} }
return 1; return 0;
error: error:
if (release_io_ports) if (release_io_ports)
release_region(0x3b0, 12); release_region(0x3b0, 12);
if (release_io_port) if (release_io_port)
release_region(0x3bf, 1); release_region(0x3bf, 1);
return 0;
iounmap(hga_vram);
pr_err("hgafb: HGA card not detected.\n");
return -EINVAL;
} }
/** /**
@ -548,13 +555,11 @@ static const struct fb_ops hgafb_ops = {
static int hgafb_probe(struct platform_device *pdev) static int hgafb_probe(struct platform_device *pdev)
{ {
struct fb_info *info; struct fb_info *info;
int ret;
if (! hga_card_detect()) { ret = hga_card_detect();
printk(KERN_INFO "hgafb: HGA card not detected.\n"); if (!ret)
if (hga_vram) return ret;
iounmap(hga_vram);
return -EINVAL;
}
printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n", printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
hga_type_name, hga_vram_len/1024); hga_type_name, hga_vram_len/1024);