From: Cliff Wickman <cpw@sgi.com>
Date: Tue, 24 Jun 2008 17:20:06 +0000 (-0700)
Subject: [IA64] Handle count==0 in sn2_ptc_proc_write()
X-Git-Tag: v2.6.26-rc8~1^2~1
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8097110d179b874d91c6495330c2b96c991e8c6e;p=linux-2.6

[IA64] Handle count==0 in sn2_ptc_proc_write()

The fix applied in e0c6d97c65e0784aade7e97b9411f245a6c543e7
"security hole in sn2_ptc_proc_write" didn't take into account
the case where count==0 (which results in a buffer underrun
when adding the trailing '\0').  Thanks to Andi Kleen for
pointing this out.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---

diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c
index 6dd886c5d8..e585f9a2af 100644
--- a/arch/ia64/sn/kernel/sn2/sn2_smp.c
+++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c
@@ -512,7 +512,7 @@ static ssize_t sn2_ptc_proc_write(struct file *file, const char __user *user, si
 	int cpu;
 	char optstr[64];
 
-	if (count > sizeof(optstr))
+	if (count == 0 || count > sizeof(optstr))
 		return -EINVAL;
 	if (copy_from_user(optstr, user, count))
 		return -EFAULT;