Hi all,
On 01/12/25 23:49, Borislav Petkov wrote:
On Mon, Dec 01, 2025 at 09:20:20AM -0800, Andrew Morton wrote:
On Wed, 12 Nov 2025 11:30:02 -0800 Harshit Mogalapalli harshit.m.mogalapalli@oracle.com wrote:
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 pageOther 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.
Then why isn't there a ima_validate_range() function there which everyone calls instead of the same check being replicated everywhere?
Thanks for the reviews.
Sure, have tried this, will send a V2 with a generic helper.
Cc: stable@vger.kernel.org Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
That was via the x86 tree so I assume the x86 team (Boris?) will be processing this patch.
Yeah, it is on my to-deal-with-after-the-merge-window pile.
But since you've forced my hand... :-P
I'll put it into mm.git's mm-hotfixes branch for now, to get a bit of testing and to generally track its progress.
--- 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."within" ;)
Thanks for spotting.
*/- 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",This error message needs to be made a lot more user-friendly.
And pls do a generic helper as suggested above which ima code calls.
Will do, thanks for the suggestion.
And by looking at the diff, there are two ima_get_kexec_buffer() functions in the tree which could use some unification too ontop.
In drivers/of/kexec.c we have:
int __init ima_get_kexec_buffer(void **addr, size_t *size) { int ret, len; unsigned long tmp_addr; unsigned long start_pfn, end_pfn; size_t tmp_size; const void *prop;
prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len); if (!prop) return -ENOENT;
ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size); if (ret) return ret;
/* Do some sanity on the returned size for the ima-kexec buffer */ if (!tmp_size) return -ENOENT;
/* * Calculate the PFNs for the buffer and ensure * they are with in addressable memory. */ start_pfn = PHYS_PFN(tmp_addr); end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1); if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) { pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n", tmp_addr, tmp_size); return -EINVAL; }
*addr = __va(tmp_addr); *size = tmp_size;
return 0; }
In arch/x86/kernel/setup.c we have something like:
int __init ima_get_kexec_buffer(void **addr, size_t *size) { if (!ima_kexec_buffer_size) return -ENOENT;
*addr = __va(ima_kexec_buffer_phys); *size = ima_kexec_buffer_size;
return 0; }
I will try to generalize common parts in another patch.
Will send a V2 adding ima_validate_range() helper.
Thanks, Harshit.
Right?
Thx.