wmi: fix kernel panic when stack protection enabled.
commitf3d83e2415445e5b157bef404d38674e9e8de169
authorCostantino Leandro <lcostantino@gmail.com>
Wed, 26 Aug 2009 21:29:28 +0000 (26 14:29 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 27 Aug 2009 03:06:53 +0000 (26 20:06 -0700)
treeadc92f5fd348427802e0768aa2aaabe9a409970d
parentce8442b55135c679809311997d1446f3bbc05de2
wmi: fix kernel panic when stack protection enabled.

Summary:
Kernel panic arise when stack protection is enabled, since strncat will
add a null terminating byte '\0'; So in functions
like this one (wmi_query_block):
        char wc[4]="WC";
....
strncat(method, block->object_id, 2);
        ...
the length of wc should be n+1 (wc[5]) or stack protection
fault will arise. This is not noticeable when stack protection is
disabled,but , isn't good either.
Config used: [CONFIG_CC_STACKPROTECTOR_ALL=y,
      CONFIG_CC_STACKPROTECTOR=y]

Panic Trace
------------
       .... stack-protector: kernel stack corrupted in : fa7b182c
       2.6.30-rc8-obelisco-generic
       call_trace:
           [<c04a6c40>] ? panic+0x45/0xd9
   [<c012925d>] ? __stack_chk_fail+0x1c/0x40
   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
   [<fa7e7000>] ? acer_wmi_init+0x00/0x61a [acer_wmi]
   [<fa7e7135>] ? acer_wmi_init+0x135/0x61a [acer_wmi]
   [<c0101159>] ? do_one_initcall+0x50+0x126

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13514

Signed-off-by: Costantino Leandro <lcostantino@gmail.com>
Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Cc: Len Brown <len.brown@intel.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/platform/x86/wmi.c