efivars: only check for duplicates on the registered list
authorMatt Fleming <matt.fleming@intel.com>
Fri, 26 Apr 2013 09:10:55 +0000 (10:10 +0100)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 26 Apr 2013 15:02:03 +0000 (08:02 -0700)
commitf464246d85d5a5c0fdbf5838b8c58ef59bd82fcc
treee0788b40695dcaa64ef2baa2367639dcdb3f4fc5
parent37b7f3c76595e23257f61bd80b223de8658617ee
efivars: only check for duplicates on the registered list

variable_is_present() accesses '__efivars' directly, but when called via
gsmi_init() Michel reports observing the following crash,

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: variable_is_present+0x55/0x170
  Call Trace:
    register_efivars+0x106/0x370
    gsmi_init+0x2ad/0x3da
    do_one_initcall+0x3f/0x170

The reason for the crash is that '__efivars' hasn't been initialised nor
has it been registered with register_efivars() by the time the google
EFI SMI driver runs.  The gsmi code uses its own struct efivars, and
therefore, a different variable list.  Fix the above crash by passing
the registered struct efivars to variable_is_present(), so that we
traverse the correct list.

Reported-by: Michel Lespinasse <walken@google.com>
Tested-by: Michel Lespinasse <walken@google.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/firmware/efivars.c