linux-kernel - [PATCH 1/2] lguest: read length of device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu,  3 Mar 2016 13:01:40 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	Rusty Russell <rusty@...tcorp.com.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc:	x86@...nel.org, lguest@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] lguest: read length of device_cap later

Read the length of the capability with type VIRTIO_PCI_CAP_DEVICE_CFG
only when we're sure we're going to need it. Which is just before the
check whether the virtio console actually has an emerg_wr field.

Signed-off-by: Paul Bolle <pebolle@...cali.nl>
---
 arch/x86/lguest/boot.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 4ba229ac3f4f..535e3197d0c7 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1258,7 +1258,7 @@ static void probe_pci_console(void)
 		u8 vndr = read_pci_config_byte(0, 1, 0, cap);
 		if (vndr == PCI_CAP_ID_VNDR) {
 			u8 type, bar;
-			u32 offset, length;
+			u32 offset;
 
 			type = read_pci_config_byte(0, 1, 0,
 			    cap + offsetof(struct virtio_pci_cap, cfg_type));
@@ -1266,15 +1266,12 @@ static void probe_pci_console(void)
 			    cap + offsetof(struct virtio_pci_cap, bar));
 			offset = read_pci_config(0, 1, 0,
 			    cap + offsetof(struct virtio_pci_cap, offset));
-			length = read_pci_config(0, 1, 0,
-			    cap + offsetof(struct virtio_pci_cap, length));
 
 			switch (type) {
 			case VIRTIO_PCI_CAP_DEVICE_CFG:
 				if (bar == 0) {
 					device_cap = cap;
 					device_offset = offset;
-					device_len = length;
 				}
 				break;
 			case VIRTIO_PCI_CAP_PCI_CFG:
@@ -1297,6 +1294,8 @@ static void probe_pci_console(void)
 	 * emerg_wr.  If it doesn't support VIRTIO_CONSOLE_F_EMERG_WRITE
 	 * it should ignore the access.
 	 */
+	device_len = read_pci_config(0, 1, 0,
+			device_cap + offsetof(struct virtio_pci_cap, length));
 	if (device_len < (offsetof(struct virtio_console_config, emerg_wr)
 			  + sizeof(u32))) {
 		printk(KERN_ERR "lguest: console missing emerg_wr field\n");
-- 
2.4.3