x86, SGI UV: TLB shootdown using broadcast assist unit, v6

v6: 6/19 close the security hole in uv_ptc_proc_write())

  > Found a potential security hole while doing that:
  > static ssize_t uv_ptc_proc_write(struct file *file, const char __user *user,
  >                              size_t count, loff_t *data)
  >     if (copy_from_user(optstr, user, count))
  >             return -EFAULT;
  >
  > is count guaranteed to never be larger than 64?

is fixed below.

It adds tlb_uv.o to the Makefile.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: mingo@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/tlb_uv.c b/arch/x86/kernel/tlb_uv.c
index b362913f0199..c503b7f04481 100644
--- a/arch/x86/kernel/tlb_uv.c
+++ b/arch/x86/kernel/tlb_uv.c
@@ -492,6 +492,8 @@ static ssize_t uv_ptc_proc_write(struct file *file, const char __user *user,
         long newmode;
         char optstr[64];
 
+        if (count > 64)
+                return -EINVAL;
         if (copy_from_user(optstr, user, count))
                 return -EFAULT;
         optstr[count - 1] = '\0';