On Fri, Apr 26, 2013 at 12:12 AM, Matt Fleming <matt.flem...@intel.com> wrote: > On 26/04/13 00:11, Michel Lespinasse wrote: >> On Thu, Apr 25, 2013 at 3:54 PM, H. Peter Anvin <h...@zytor.com> wrote: >>> On 04/25/2013 03:53 PM, Michel Lespinasse wrote: >>>> Well, I don't know if this is related, but commit e971318bbed6 broke >>>> the google EFI SMI driver with >>>> BUG: unable to handle kernel NULL pointer dereference at (null) >>>> IP: [<ffffffff814a7245>] variable_is_present+0x55/0x170 >>>> Call Trace: >>>> [<ffffffff814a9936>] register_efivars+0x106/0x370 >>>> [<ffffffff818ff430>] ? firmware_map_add_early+0xb1/0xb1 >>>> [<ffffffff818ff6dd>] gsmi_init+0x2ad/0x3da >>>> [<ffffffff8100020f>] do_one_initcall+0x3f/0x170 >>>> ... >>> >>> I don't know either. Could you test this patch and see if it does anything? >> >> Nope, still seeing the crash with this patch applied. > > Could you try the following patch against Linus' tree? The bug you've > found and the changes in the pull request are unrelated. > > diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c > index 182ce94..2a4f619 100644 > --- a/drivers/firmware/efivars.c > +++ b/drivers/firmware/efivars.c > @@ -1635,6 +1635,9 @@ static bool variable_is_present(efi_char16_t > *variable_name, efi_guid_t *vendor) > unsigned long strsize1, strsize2; > bool found = false; > > + if (list_empty(&efivars->list)) > + return false; > + > strsize1 = ucs2_strsize(variable_name, 1024); > list_for_each_entry_safe(entry, n, &efivars->list, list) { > strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
Still seeing the crash. I went and compared the crash dump with the vmlinux disassembly; the issue is a NULL pointer dereference in list_for_each_entry_safe(). list_empty() checks that the head node points to itself, but here the head node has NULL. I think this may be due to gsmi_init() being called before efivars_init(). Not sure what's the proper fix though. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/