efi-bgrt: Add error handling; inform the user when ignoring the BGRT

Gracefully handle failures to allocate memory for the image, which might
be arbitrarily large.

efi_bgrt_init can fail in various ways as well, usually because the
BIOS-provided BGRT structure does not match expectations.  Add
appropriate error messages rather than failing silently.

Reported-by: Srihari Vijayaraghavan <linux.bug.reporting@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=81321
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/arch/x86/platform/efi/efi-bgrt.c b/arch/x86/platform/efi/efi-bgrt.c
index f15103dff4b43f04e16ff8bbd59354435aec4cb7..d143d216d52bec69b912128d88c3283cd0122c6c 100644 (file)
--- a/arch/x86/platform/efi/efi-bgrt.c
+++ b/arch/x86/platform/efi/efi-bgrt.c
@@ -40,20 +40,40 @@ void __init efi_bgrt_init(void)
        if (ACPI_FAILURE(status))
                return;
 
-       if (bgrt_tab->header.length < sizeof(*bgrt_tab))
+       if (bgrt_tab->header.length < sizeof(*bgrt_tab)) {
+               pr_err("Ignoring BGRT: invalid length %u (expected %zu)\n",
+                      bgrt_tab->header.length, sizeof(*bgrt_tab));
                return;
-       if (bgrt_tab->version != 1 || bgrt_tab->status != 1)
+       }
+       if (bgrt_tab->version != 1) {
+               pr_err("Ignoring BGRT: invalid version %u (expected 1)\n",
+                      bgrt_tab->version);
+               return;
+       }
+       if (bgrt_tab->status != 1) {
+               pr_err("Ignoring BGRT: invalid status %u (expected 1)\n",
+                      bgrt_tab->status);
+               return;
+       }
+       if (bgrt_tab->image_type != 0) {
+               pr_err("Ignoring BGRT: invalid image type %u (expected 0)\n",
+                      bgrt_tab->image_type);
                return;
-       if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address)
+       }
+       if (!bgrt_tab->image_address) {
+               pr_err("Ignoring BGRT: null image address\n");
                return;
+       }
 
        image = efi_lookup_mapped_addr(bgrt_tab->image_address);
        if (!image) {
                image = early_memremap(bgrt_tab->image_address,
                                       sizeof(bmp_header));
                ioremapped = true;
-               if (!image)
+               if (!image) {
+                       pr_err("Ignoring BGRT: failed to map image header memory\n");
                        return;
+               }
        }
 
        memcpy_fromio(&bmp_header, image, sizeof(bmp_header));
@@ -61,14 +81,18 @@ void __init efi_bgrt_init(void)
                early_iounmap(image, sizeof(bmp_header));
        bgrt_image_size = bmp_header.size;
 
-       bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL);
-       if (!bgrt_image)
+       bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL | __GFP_NOWARN);
+       if (!bgrt_image) {
+               pr_err("Ignoring BGRT: failed to allocate memory for image (wanted %zu bytes)\n",
+                      bgrt_image_size);
                return;
+       }
 
        if (ioremapped) {
                image = early_memremap(bgrt_tab->image_address,
                                       bmp_header.size);
                if (!image) {
+                       pr_err("Ignoring BGRT: failed to map image memory\n");
                        kfree(bgrt_image);
                        bgrt_image = NULL;
                        return;