Commit fe93fa1b authored Nov 05, 2024 by Ard Biesheuvel Committed by Qi Xi Nov 05, 2024

efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption

mainline inclusion
from mainline-v6.12-rc1
commit 77d48d39e99170b528e4f2e9fc5d1d64cdedd386
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYQSJ
CVE: CVE-2024-49858

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77d48d39e99170b528e4f2e9fc5d1d64cdedd386



--------------------------------

The TPM event log table is a Linux specific construct, where the data
produced by the GetEventLog() boot service is cached in memory, and
passed on to the OS using an EFI configuration table.

The use of EFI_LOADER_DATA here results in the region being left
unreserved in the E820 memory map constructed by the EFI stub, and this
is the memory description that is passed on to the incoming kernel by
kexec, which is therefore unaware that the region should be reserved.

Even though the utility of the TPM2 event log after a kexec is
questionable, any corruption might send the parsing code off into the
weeds and crash the kernel. So let's use EFI_ACPI_RECLAIM_MEMORY
instead, which is always treated as reserved by the E820 conversion
logic.

Cc: <stable@vger.kernel.org>
Reported-by: Breno Leitao <leitao@debian.org>
Tested-by: Usama Arif <usamaarif642@gmail.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>

parent c8b75210

drivers/firmware/efi/libstub/tpm.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -115,7 +115,7 @@ void efi_retrieve_tpm2_eventlog(void)
		}

		/* Allocate space for the logs and copy them. */
		status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
		status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
		sizeof(log_tbl) + log_size, (void *)&log_tbl);

		if (status != EFI_SUCCESS) {