[PATCH] race condition in procfs

[Grzegorz Nosek]

Hello,

I found a race condition in procfs on SMP systems. The result is an
oops in processes like pidof. Apparently ->proc_read() gets passed a
potentially NULL pointer. The following micro-patch seems to fix it.

Best regards,
 Grzegorz Nosek

--- linux-2.6/fs/proc/base.c.orig 2005-11-25 00:07:43.000000000 +0100
+++ linux-2.6/fs/proc/base.c      2005-11-28 11:44:11.000000000 +0100
@@ -718,6 +718,9 @@
       ssize_t length;
       struct task_struct *task = proc_task(inode);

+       if (!task)
+               return -ENOENT;
+
       if (count > PROC_BLOCK_SIZE)
               count = PROC_BLOCK_SIZE;
       if (!(page = __get_free_page(GFP_KERNEL)))
-
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