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;
--
2.50.1