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 <m...@suse.com>
> > >
> > > 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.flem...@intel.com>
> 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 <fcro...@suse.com>
> Cc: Matthew Garrett <mj...@srcf.ucam.org>
> Cc: Josh Boyer <jwbo...@redhat.com>
> Cc: Michael Schroeder <m...@suse.com>
> Cc: Lee, Chun-Yi <j...@suse.com>
> Cc: Lingzhu Xiang <lxi...@redhat.com>
> Signed-off-by: Matt Fleming <matt.flem...@intel.com>
> ---
> 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,
--
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