From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: [PATCH 1/1] efi/libstub: tpm: zero initialize pointer variables for mixed mode Date: Tue, 13 Mar 2018 16:10:32 +0100 Message-ID: <1a72c53b-76fe-a119-3283-0950b8f758e7@redhat.com> References: <20180313140922.17266-1-ard.biesheuvel@linaro.org> <20180313140922.17266-2-ard.biesheuvel@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180313140922.17266-2-ard.biesheuvel@linaro.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Ard Biesheuvel , linux-efi@vger.kernel.org, Ingo Molnar , Thomas Gleixner Cc: hdegoede@redhat.com, tweek@google.com, jarkko.sakkinen@linux.intel.com, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, tpmdd-devel@lists.sourceforge.net List-Id: tpmdd-devel@lists.sourceforge.net [adding linux-integrity and tpmdd-devel since this was discussed in these ML too] On 03/13/2018 03:09 PM, Ard Biesheuvel wrote: > As reported by Jeremy, running the new TPM libstub code in mixed mode > (i.e., 64-bit kernel on 32-bit UEFI) results in hangs when invoking > the TCG2 protocol, or when accessing the log_tbl pool allocation. > > The reason turns out to be that in both cases, the 64-bit pointer > variables are not fully initialized by the 32-bit EFI code, and so > we should take care to zero initialize these variables beforehand, > or we'll end up dereferencing bogus pointers. > > Reported-by: Jeremy Cline > Signed-off-by: Ard Biesheuvel > --- > drivers/firmware/efi/libstub/tpm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c > index da661bf8cb96..13c1edd37e96 100644 > --- a/drivers/firmware/efi/libstub/tpm.c > +++ b/drivers/firmware/efi/libstub/tpm.c > @@ -68,11 +68,11 @@ void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg) > efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID; > efi_status_t status; > efi_physical_addr_t log_location, log_last_entry; > - struct linux_efi_tpm_eventlog *log_tbl; > + struct linux_efi_tpm_eventlog *log_tbl = NULL; > unsigned long first_entry_addr, last_entry_addr; > size_t log_size, last_entry_size; > efi_bool_t truncated; > - void *tcg2_protocol; > + void *tcg2_protocol = NULL; > > status = efi_call_early(locate_protocol, &tcg2_guid, NULL, > &tcg2_protocol); > Looks good to me. Reviewed-by: Javier Martinez Canillas Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat