From b15b244d6e6e20964bd4b85306722cb60c3c0809 Mon Sep 17 00:00:00 2001

From: Benjamin Herrenschmidt benh@kernel.crashing.org Date: Mon, 2 Apr 2012 13:28:18 +1000 Subject:

Under some circumstances, pci_map_rom() can return a valid mapping but a size of 0 (if it cannot find an image in the header).

This causes nouveau to try to kmalloc() a 0 sized pointer and dereference it, which crashes.

Signed-off-by: Benjamin Herrenschmidt benh@kernel.crashing.org ---

Please send to Linus asap, without this, it crashes on the G5

drivers/gpu/drm/nouveau/nouveau_bios.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c b/drivers/gpu/drm/nouveau/nouveau_bios.c index 637afe7..80963d0 100644 --- a/drivers/gpu/drm/nouveau/nouveau_bios.c +++ b/drivers/gpu/drm/nouveau/nouveau_bios.c @@ -177,14 +177,15 @@ bios_shadow_pci(struct nvbios *bios)

if (!pci_enable_rom(pdev)) { void __iomem *rom = pci_map_rom(pdev, &length); - if (rom) { + if (rom && length) { bios->data = kmalloc(length, GFP_KERNEL); if (bios->data) { memcpy_fromio(bios->data, rom, length); bios->length = length; } - pci_unmap_rom(pdev, rom); } + if (rom) + pci_unmap_rom(pdev, rom);

pci_disable_rom(pdev); }