[PATCH] 2.4: [POWERPC] CHRP: Fix possible NULL pointer dereference

[dann frazier <dannf@hp.com>]

This is a 2.4 backport of a linux-2.6 change by Cyrill Gorcunov.
(commit 9ac71d00398674aaec664f30559f0a21d963862f)

CVE-2007-6694 was assigned for this issue.
This backport has been compile-tested only.

Commit log from 2.6 follows.

    This fixes a possible NULL pointer dereference inside of strncmp() if
    of_get_property() fails.

Signed-off-by: dann frazier <dannf@hp.com>

diff --git a/arch/ppc/platforms/chrp_setup.c b/arch/ppc/platforms/chrp_setup.c
index 0ffbbd2..28747db 100644
--- a/arch/ppc/platforms/chrp_setup.c
+++ b/arch/ppc/platforms/chrp_setup.c
@@ -121,7 +121,7 @@ chrp_show_cpuinfo(struct seq_file *m)
 	seq_printf(m, "machine\t\t: CHRP %s\n", model);
 
 	/* longtrail (goldengate) stuff */
-	if (!strncmp(model, "IBM,LongTrail", 13)) {
+	if (model && !strncmp(model, "IBM,LongTrail", 13)) {
 		/* VLSI VAS96011/12 `Golden Gate 2' */
 		/* Memory banks */
 		sdramen = (in_le32((unsigned *)(gg2_pci_config_base+
@@ -210,14 +210,20 @@ static void __init sio_fixup_irq(const char *name, u8 device, u8 level,
 static void __init sio_init(void)
 {
 	struct device_node *root;
+	const char *model;
 
-	if ((root = find_path_device("/")) &&
-	    !strncmp(get_property(root, "model", NULL), "IBM,LongTrail", 13)) {
+	root = find_path_device("/");
+	if (!root)
+		return;
+
+	model = get_property(root, "model", NULL);
+	if (model && !strncmp(model, "IBM,LongTrail", 13)) {
 		/* logical device 0 (KBC/Keyboard) */
 		sio_fixup_irq("keyboard", 0, 1, 2);
 		/* select logical device 1 (KBC/Mouse) */
 		sio_fixup_irq("mouse", 1, 12, 2);
 	}
+
 }
 
 
-- 
1.5.4