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.
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 Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com --- Have tested the kexec for x86 kernel with IMA_KEXEC enabled and the above patch works good. Paul initially reported this on 6.12 kernel but I was able to reproduce this on 6.18, so I tried replicating how this was fixed in drivers/of/kexec.c --- arch/x86/kernel/setup.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 1b2edd07a3e1..fcef197d180e 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -439,9 +439,23 @@ int __init ima_free_kexec_buffer(void)
int __init ima_get_kexec_buffer(void **addr, size_t *size) { + unsigned long start_pfn, end_pfn; + if (!ima_kexec_buffer_size) return -ENOENT;
+ /* + * Calculate the PFNs for the buffer and ensure + * they are with in addressable memory. + */ + start_pfn = PFN_DOWN(ima_kexec_buffer_phys); + end_pfn = PFN_DOWN(ima_kexec_buffer_phys + ima_kexec_buffer_size - 1); + if (!pfn_range_is_mapped(start_pfn, end_pfn)) { + pr_warn("IMA buffer at 0x%llx, size = 0x%zx beyond memory\n", + ima_kexec_buffer_phys, ima_kexec_buffer_size); + return -EINVAL; + } + *addr = __va(ima_kexec_buffer_phys); *size = ima_kexec_buffer_size;