於 五，2013-03-01 於 16:31 +0000，Matt Fleming 提到： > On Fri, 2013-03-01 at 15:17 +0000, Matt Fleming wrote: > > On Fri, 2013-03-01 at 11:20 +0800, Lee, Chun-Yi wrote: > > > From: Michael Schroeder <mls@xxxxxxxx> > > > > > > On HP z220 system (firmware version 1.54), some EFI variables are incorrectly > > > named : > > > > > > ls -d /sys/firmware/efi/vars/*8be4d* | grep -v -- -8be returns > > > /sys/firmware/efi/vars/dbxDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/KEKDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/SecureBoot-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/SetupMode-Information8be4df61-93ca-11d2-aa0d-00e098032b8c > > > > > > That causes by the following statement in efivar_create_sysfs_entry function: > > > > > > *(short_name + strlen(short_name)) = '-'; > > > efi_guid_unparse(vendor_guid, short_name + strlen(short_name)); > > > > > > The trailing \0 is overwritten with '-', but the next char doesn't seem to be a \0 > > > as well for HP. So, the second strlen return the point of next '\0', causes there > > > have garbage string attached before GUID. > > > > > > Tested on On HP z220. > > > > What's more likely happening here is that GetNextVariable() is broken on > > this HP firmware and variable_name_size is too big for the given > > variable in variable_name. We've seen other reports of similar bugs, > > > > https://bugzilla.kernel.org/show_bug.cgi?id=47631 > > > > > > Could someone try this patch against Linus' tree? > > Urgh, and here's a version that isn't utterly, utterly broken... Thanks for Matt's patch, we will try it! Joey Lee > > --- > > >From 4b2ef72bca72039717efe4570ec858a86d565b34 Mon Sep 17 00:00:00 2001 > From: Matt Fleming <matt.fleming@xxxxxxxxx> > Date: Fri, 1 Mar 2013 14:49:12 +0000 > Subject: [PATCH] efivars: Sanitise string length returned by > GetNextVariableName() > > Some buggy firmware implementations return a string length from > GetNextVariableName() that is actually larger than the string in > 'variable_name', as Michael Schroeder writes, > > > On HP z220 system (firmware version 1.54), some EFI variables are > > incorrectly named : > > > > ls -d /sys/firmware/efi/vars/*8be4d* | grep -v -- -8be returns > > /sys/firmware/efi/vars/dbxDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > /sys/firmware/efi/vars/KEKDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > /sys/firmware/efi/vars/SecureBoot-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > /sys/firmware/efi/vars/SetupMode-Information8be4df61-93ca-11d2-aa0d-00e098032b8c > > Since 'variable_name' is a string, we can validate its size by > searching for the terminating NULL character. > > Reported-by: Frederic Crozat <fcrozat@xxxxxxxx> > Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx> > Cc: Josh Boyer <jwboyer@xxxxxxxxxx> > Cc: Michael Schroeder <mls@xxxxxxxx> > Cc: Lee, Chun-Yi <jlee@xxxxxxxx> > Cc: Lingzhu Xiang <lxiang@xxxxxxxxxx> > Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> > --- > drivers/firmware/efivars.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c > index 7320bf8..ab477b8 100644 > --- a/drivers/firmware/efivars.c > +++ b/drivers/firmware/efivars.c > @@ -1895,6 +1895,33 @@ void unregister_efivars(struct efivars *efivars) > } > EXPORT_SYMBOL_GPL(unregister_efivars); > > +/* > + * Sanity check size of a variable name. > + */ > +static unsigned long sanity_check_size(efi_char16_t *variable_name, > + unsigned long variable_name_size) > +{ > + unsigned long len; > + efi_char16_t c; > + > + /* > + * The variable name is, by definition, a NULL-terminated > + * string, so make absolutely sure that variable_name_size is > + * the value we expect it to be. If not, return the real size. > + */ > + for (len = 2; len <= variable_name_size; len += sizeof(c)) { > + c = variable_name[(len / sizeof(c)) - 1]; > + if (!c) > + break; > + } > + > + > + if (len != variable_name_size) > + printk(KERN_WARNING "efivars: bogus variable_name_size: %lu %lu\n", len, variable_name_size); > + > + return min(len, variable_name_size); > +} > + > int register_efivars(struct efivars *efivars, > const struct efivar_operations *ops, > struct kobject *parent_kobj) > @@ -1941,8 +1968,11 @@ int register_efivars(struct efivars *efivars, > status = ops->get_next_variable(&variable_name_size, > variable_name, > &vendor_guid); > + > switch (status) { > case EFI_SUCCESS: > + variable_name_size = sanity_check_size(variable_name, > + variable_name_size); > efivar_create_sysfs_entry(efivars, > variable_name_size, > variable_name, -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
