Re: [PATCH 02/36] usercopy: Include offset in overflow report

On Wed, Jan 10, 2018 at 7:25 AM, Christopher Lameter [off-list ref] wrote:

On Tue, 9 Jan 2018, Kees Cook wrote:

quoted

-static void report_usercopy(unsigned long len, bool to_user, const char *type)
+int report_usercopy(const char *name, const char *detail, bool to_user,
+                 unsigned long offset, unsigned long len)
 {
-     pr_emerg("kernel memory %s attempt detected %s '%s' (%lu bytes)\n",
+     pr_emerg("kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)\n",
              to_user ? "exposure" : "overwrite",
-             to_user ? "from" : "to", type ? : "unknown", len);
+             to_user ? "from" : "to",
+             name ? : "unknown?!",
+             detail ? " '" : "", detail ? : "", detail ? "'" : "",
+             offset, len);
      /*
       * For greater effect, it would be nice to do do_group_exit(),
       * but BUG() actually hooks all the lock-breaking and per-arch
       * Oops code, so that is used here instead.
       */
      BUG();

Should this be a WARN() or so? Or some configuration that changes
BUG() behavior? Otherwise

This BUG() is the existing behavior, with the new behavior taking the
WARN() route in a following patch.

quoted

+
+     return -1;

This return code will never be returned.

Why a return code at all? Maybe I will see that in the following patches?

I was trying to simplify the callers, but I agree, the result is
rather ugly. I'll see if I can fix this up.

-Kees

-- 
Kees Cook
Pixel Security

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