When the second-stage kernel is booted via kexec with a limiting command line such as "mem=<size>", the physical range that contains the carried over IMA measurement list may fall outside the truncated RAM leading to a kernel panic.
BUG: unable to handle page fault for address: ffff97793ff47000 RIP: ima_restore_measurement_list+0xdc/0x45a #PF: error_code(0x0000) – not-present page
Other architectures already validate the range with page_is_ram(), as done in commit cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer against memory bounds") do a similar check on x86.
Without carrying the measurement list across kexec, the attestation would fail.
Cc: stable@vger.kernel.org Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec") Reported-by: Paul Webb paul.x.webb@oracle.com Reviewed-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com --- V1-> V2: Added a line about carrying measure list across kexec based on suggestion from Mimi Zohar. Made use to the new generic helper [Suggestion from Borislav]
V2-> V3: Add RB from Mimi Zohar. --- arch/x86/kernel/setup.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 1b2edd07a3e1..383d4a4784f5 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -439,9 +439,15 @@ int __init ima_free_kexec_buffer(void)
int __init ima_get_kexec_buffer(void **addr, size_t *size) { + int ret; + if (!ima_kexec_buffer_size) return -ENOENT;
+ ret = ima_validate_range(ima_kexec_buffer_phys, ima_kexec_buffer_size); + if (ret) + return ret; + *addr = __va(ima_kexec_buffer_phys); *size = ima_kexec_buffer_size;