drm/nouveau/bios: fetch full 4KiB block to determine ACPI ROM image size

Buggy firmware leads to bad things happening otherwise..

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/gpu/drm/nouveau/core/subdev/bios/base.c b/drivers/gpu/drm/nouveau/core/subdev/bios/base.c
index 3a84ad4f171a..70ca7d5a1aa1 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/bios/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/bios/base.c
@@ -192,7 +192,6 @@ nouveau_bios_shadow_acpi(struct nouveau_bios *bios)
 {
         struct pci_dev *pdev = nv_device(bios)->pdev;
         int ret, cnt, i;
-        u8  data[3];
 
         if (!nouveau_acpi_rom_supported(pdev)) {
                 bios->data = NULL;
@@ -200,8 +199,13 @@ nouveau_bios_shadow_acpi(struct nouveau_bios *bios)
         }
 
         bios->size = 0;
-        if (nouveau_acpi_get_bios_chunk(data, 0, 3) == 3)
-                bios->size = data[2] * 512;
+        bios->data = kmalloc(4096, GFP_KERNEL);
+        if (bios->data) {
+                if (nouveau_acpi_get_bios_chunk(bios->data, 0, 4096) == 4096)
+                        bios->size = bios->data[2] * 512;
+                kfree(bios->data);
+        }
+
         if (!bios->size)
                 return;