From: Igor Matheus Andrade Torrente igormtorrente@gmail.com
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.
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.o... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/video/fbdev/hgafb.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
--- a/drivers/video/fbdev/hgafb.c +++ 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; error: if (release_io_ports) release_region(0x3b0, 12); if (release_io_port) 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) { struct fb_info *info; + int ret;
- if (! hga_card_detect()) { - printk(KERN_INFO "hgafb: HGA card not detected.\n"); - if (hga_vram) - iounmap(hga_vram); - return -EINVAL; - } + 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);