From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.5 65/88] x86/sysfb_efi: Fix valid BAR address range check Date: Mon, 9 May 2016 09:21:54 +0200 Message-ID: <20160509071955.373943811@linuxfoundation.org> References: <20160509071952.129092535@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Return-path: In-Reply-To: <20160509071952.129092535@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Wang YanQing , Matt Fleming , Peter Jones , Ard Biesheuvel , David Herrmann , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Tomi Valkeinen , linux-efi@vger.kernel.org, Ingo Molnar List-Id: linux-efi@vger.kernel.org 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wang YanQing commit c10fcb14c7afd6688c7b197a814358fecf244222 upstream. The code for checking whether a BAR address range is valid will break out of the loop when a start address of 0x0 is encountered. This behaviour is wrong since by breaking out of the loop we may miss the BAR that describes the EFI frame buffer in a later iteration. Because of this bug I can't use video=efifb: boot parameter to get efifb on my new ThinkPad E550 for my old linux system hard disk with 3.10 kernel. In 3.10, efifb is the only choice due to DRM/I915 not supporting the GPU. This patch also add a trivial optimization to break out after we find the frame buffer address range without testing later BARs. Signed-off-by: Wang YanQing [ Rewrote changelog. ] Signed-off-by: Matt Fleming Reviewed-by: Peter Jones Cc: Ard Biesheuvel Cc: David Herrmann Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tomi Valkeinen Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1462454061-21561-2-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/sysfb_efi.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/sysfb_efi.c +++ b/arch/x86/kernel/sysfb_efi.c @@ -106,14 +106,24 @@ static int __init efifb_set_system(const continue; for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) { resource_size_t start, end; + unsigned long flags; + + flags = pci_resource_flags(dev, i); + if (!(flags & IORESOURCE_MEM)) + continue; + + if (flags & IORESOURCE_UNSET) + continue; + + if (pci_resource_len(dev, i) == 0) + continue; start = pci_resource_start(dev, i); - if (start == 0) - break; end = pci_resource_end(dev, i); if (screen_info.lfb_base >= start && screen_info.lfb_base < end) { found_bar = 1; + break; } } }