[PATCH 6.12 093/265] ima: verify the previous kernels IMA buffer lies in addressable RAM

Greg Kroah-Hartman
2026-03-12T20:17:39Z

From: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>

[ Upstream commit 10d1c75ed4382a8e79874379caa2ead8952734f9 ]

Patch series "Address page fault in ima_restore_measurement_list()", v3.

When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=<size>" we observe a pafe fault that happens.

BUG: unable to handle page fault for address: ffff97793ff47000
RIP: ima_restore_measurement_list+0xdc/0x45a
#PF: error_code(0x0000) not-present page

This happens on x86_64 only, as this is already fixed in aarch64 in
commit: cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds")

This patch (of 3):

When the second-stage kernel is booted with a limiting command line (e.g.
"mem=<size>"), the IMA measurement buffer handed over from the previous
kernel may fall outside the addressable RAM of the new kernel. Accessing
such a buffer can fault during early restore.

Introduce a small generic helper, ima_validate_range(), which verifies
that a physical [start, end] range for the previous-kernel IMA buffer lies
within addressable memory:
- On x86, use pfn_range_is_mapped().
- On OF based architectures, use page_is_ram().

Link: https://lkml.kernel.org/r/20251231061609.907170-1-harshit.m.mogalapalli@oracle.com
Link: https://lkml.kernel.org/r/20251231061609.907170-2-harshit.m.mogalapalli@oracle.com
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: guoweikang <guoweikang.kernel@gmail.com>
Cc: Henry Willard <henry.willard@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Jonathan McDowell <noodles@fb.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Webb <paul.x.webb@oracle.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Yifei Liu <yifei.l.liu@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/ima.h | 1 +
security/integrity/ima/ima_kexec.c | 35 ++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 8e29cb4e6a01d..abf8923f8fc51 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -69,6 +69,7 @@ static inline int ima_measure_critical_data(const char *event_label,
#ifdef CONFIG_HAVE_IMA_KEXEC
int __init ima_free_kexec_buffer(void);
int __init ima_get_kexec_buffer(void **addr, size_t *size);
+int ima_validate_range(phys_addr_t phys, size_t size);
#endif

#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index a22eeac9320aa..c9e5b1d6b0ab8 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -12,6 +12,8 @@
#include <linux/kexec.h>
#include <linux/of.h>
#include <linux/ima.h>
+#include <linux/mm.h>
+#include <linux/overflow.h>
#include <linux/reboot.h>
#include <asm/page.h>
#include "ima.h"
@@ -238,3 +240,36 @@ void __init ima_load_kexec_buffer(void)
pr_debug("Error restoring the measurement list: %d\n", rc);
}
}
+
+/*
+ * ima_validate_range - verify a physical buffer lies in addressable RAM
+ * @phys: physical start address of the buffer from previous kernel
+ * @size: size of the buffer
+ *
+ * On success return 0. On failure returns -EINVAL so callers can skip
+ * restoring.
+ */
+int ima_validate_range(phys_addr_t phys, size_t size)
+{
+ unsigned long start_pfn, end_pfn;
+ phys_addr_t end_phys;
+
+ if (check_add_overflow(phys, (phys_addr_t)size - 1, &end_phys))
+ return -EINVAL;
+
+ start_pfn = PHYS_PFN(phys);
+ end_pfn = PHYS_PFN(end_phys);
+
+#ifdef CONFIG_X86
+ if (!pfn_range_is_mapped(start_pfn, end_pfn))
+#else
+ if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn))
+#endif
+ {
+ pr_warn("IMA: previous kernel measurement buffer %pa (size 0x%zx) lies outside available memory\n",
+ &phys, size);
+ return -EINVAL;
+ }
+
+ return 0;
+}
--
2.51.0