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Subject[PATCH 4.17 083/220] efi/libstub/tpm: Initialize efi_physical_addr_t vars to zero for mixed mode
4.17-stable review patch.  If anyone has any objections, please let me know.


From: Hans de Goede <>

commit 52e1cf2d19c2e62e6a81b8de3f7320d033917dd5 upstream.


79832f0b5f71 ("efi/libstub/tpm: Initialize pointer variables to zero for mixed mode")

fixes a problem with the tpm code on mixed mode (64-bit kernel on 32-bit UEFI),
where 64-bit pointer variables are not fully initialized by the 32-bit EFI code.

A similar problem applies to the efi_physical_addr_t variables which
are written by the ->get_event_log() EFI call. Even though efi_physical_addr_t
is 64-bit everywhere, it seems that some 32-bit UEFI implementations only
fill in the lower 32 bits when passed a pointer to an efi_physical_addr_t
to fill.

This commit initializes these to 0 to, to ensure the upper 32 bits are
0 in mixed mode. This fixes recent kernels sometimes hanging during
early boot on mixed mode UEFI systems.

Signed-off-by: Hans de Goede <>
Signed-off-by: Ard Biesheuvel <>
Cc: <> # v4.16+
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Thomas Gleixner <>
Signed-off-by: Ingo Molnar <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/firmware/efi/libstub/tpm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/firmware/efi/libstub/tpm.c
+++ b/drivers/firmware/efi/libstub/tpm.c
@@ -64,7 +64,7 @@ void efi_retrieve_tpm2_eventlog_1_2(efi_
efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
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;
+ efi_physical_addr_t log_location = 0, log_last_entry = 0;
struct linux_efi_tpm_eventlog *log_tbl = NULL;
unsigned long first_entry_addr, last_entry_addr;
size_t log_size, last_entry_size;

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