[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>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c
index 6dd886c5d860..e585f9a2afb9 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;