From f464246d85d5a5c0fdbf5838b8c58ef59bd82fcc Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Fri, 26 Apr 2013 10:10:55 +0100 Subject: 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 Tested-by: Michel Lespinasse Cc: Mike Waychison Cc: Matthew Garrett Cc: Seiji Aguchi Signed-off-by: Matt Fleming Signed-off-by: Linus Torvalds --- drivers/firmware/efivars.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 182ce947117..f4baa11d364 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -1628,10 +1628,11 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, return count; } -static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor) +static bool variable_is_present(struct efivars *efivars, + efi_char16_t *variable_name, + efi_guid_t *vendor) { struct efivar_entry *entry, *n; - struct efivars *efivars = &__efivars; unsigned long strsize1, strsize2; bool found = false; @@ -1703,8 +1704,8 @@ static void efivar_update_sysfs_entries(struct work_struct *work) if (status != EFI_SUCCESS) { break; } else { - if (!variable_is_present(variable_name, - &vendor)) { + if (!variable_is_present(efivars, + variable_name, &vendor)) { found = true; break; } @@ -2008,7 +2009,8 @@ int register_efivars(struct efivars *efivars, * we'll ever see a different variable name, * and may end up looping here forever. */ - if (variable_is_present(variable_name, &vendor_guid)) { + if (variable_is_present(efivars, variable_name, + &vendor_guid)) { dup_variable_bug(variable_name, &vendor_guid, variable_name_size); status = EFI_NOT_FOUND; -- cgit v1.2.3