[PATCH] x86/mm/sme: fix the kdump kernel breakage on SME system when CONFIG_IMA_KEXEC=y

Baoquan He
2024-08-26T02:45:11Z

Recently, it's reported that kdump kernel is broken during bootup on
SME system when CONFIG_IMA_KEXEC=y. When debugging, I noticed this
can be traced back to commit ("b69a2afd5afc x86/kexec: Carry forward
IMA measurement log on kexec"). Just nobody ever tested it on SME
system when enabling CONFIG_IMA_KEXEC.

--------------------------------------------------
ima: No TPM chip found, activating TPM-bypass!
Loading compiled-in module X.509 certificates
Loaded X.509 cert 'Build time autogenerated kernel key: 18ae0bc7e79b64700122bb1d6a904b070fef2656'
ima: Allocated hash algorithm: sha256
Oops: general protection fault, probably for non-canonical address 0xcfacfdfe6660003e: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-rc2+ #14
Hardware name: Dell Inc. PowerEdge R7425/02MJ3T, BIOS 1.20.0 05/03/2023
RIP: 0010:ima_restore_measurement_list+0xdc/0x420
Code: ff 48 c7 85 10 ff ff ff 00 00 00 00 48 c7 85 18 ff ff ff 00 00 00 00 48 85 f6 0f 84 09 03 00 00 48 83 fa 17 0f 86 ff 02 00 00 <66> 83 3e 01 49 89 f4 0f 85 90 94 7d 00 48 83 7e 10 ff 0f 84 74 94
RSP: 0018:ffffc90000053c80 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffffc90000053d03 RCX: 0000000000000000
RDX: e48066052d5df359 RSI: cfacfdfe6660003e RDI: cfacfdfe66600056
RBP: ffffc90000053d80 R08: 0000000000000000 R09: ffffffff82de1a88
R10: ffffc90000053da0 R11: 0000000000000003 R12: 00000000000001a4
R13: ffffc90000053df0 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888040200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2c744050e8 CR3: 000080004110e000 CR4: 00000000003506b0
Call Trace:
<TASK>
? show_trace_log_lvl+0x1b0/0x2f0
? show_trace_log_lvl+0x1b0/0x2f0
? ima_load_kexec_buffer+0x6e/0xf0
? __die_body.cold+0x8/0x12
? die_addr+0x3c/0x60
? exc_general_protection+0x178/0x410
? asm_exc_general_protection+0x26/0x30
? ima_restore_measurement_list+0xdc/0x420
? vprintk_emit+0x1f0/0x270
? ima_load_kexec_buffer+0x6e/0xf0
ima_load_kexec_buffer+0x6e/0xf0
ima_init+0x52/0xb0
? __pfx_init_ima+0x10/0x10
init_ima+0x26/0xc0
? __pfx_init_ima+0x10/0x10
do_one_initcall+0x5b/0x300
do_initcalls+0xdf/0x100
? __pfx_kernel_init+0x10/0x10
kernel_init_freeable+0x147/0x1a0
kernel_init+0x1a/0x140
ret_from_fork+0x34/0x50
? __pfx_kernel_init+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ima_restore_measurement_list+0xdc/0x420
Code: ff 48 c7 85 10 ff ff ff 00 00 00 00 48 c7 85 18 ff ff ff 00 00 00 00 48 85 f6 0f 84 09 03 00 00 48 83 fa 17 0f 86 ff 02 00 00 <66> 83 3e 01 49 89 f4 0f 85 90 94 7d 00 48 83 7e 10 ff 0f 84 74 94
RSP: 0018:ffffc90000053c80 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffffc90000053d03 RCX: 0000000000000000
RDX: e48066052d5df359 RSI: cfacfdfe6660003e RDI: cfacfdfe66600056
RBP: ffffc90000053d80 R08: 0000000000000000 R09: ffffffff82de1a88
R10: ffffc90000053da0 R11: 0000000000000003 R12: 00000000000001a4
R13: ffffc90000053df0 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888040200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2c744050e8 CR3: 000080004110e000 CR4: 00000000003506b0
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled
Rebooting in 10 seconds..

From debugging printing, the stored addr and size of ima_kexec buffer
are not decrypted correctly like:
------
ima: ima_load_kexec_buffer, buffer:0xcfacfdfe6660003e, size:0xe48066052d5df359
------

There are three pieces of setup_data info passed to kexec/kdump kernel:
SETUP_EFI, SETUP_IMA and SETUP_RNG_SEED. However, among them, only
ima_kexec buffer suffered from the incorrect decryption. After
debugging, it's because of the code bug in early_memremap_is_setup_data()
where checking the embedded content inside setup_data takes wrong range
calculation.

The length of efi data, rng_seed and ima_kexec are 0x70, 0x20, 0x10,
and the length of setup_data is 0x10. When checking if data is inside
the embedded conent of setup_data, the starting address of efi data and
rng_seed happened to land in the wrong calculated range. While the
ima_kexec's starting address unluckily doesn't pass the checking, then
error occurred.

Here fix the code bug to make kexec/kdump kernel boot up successfully.

Fixes: 8f716c9b5feb ("x86/mm: Add support to access boot related data in the clear")
Signed-off-by: Baoquan He <bhe@redhat.com>
---
arch/x86/mm/ioremap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index aa7d279321ea..7953c4a1d28d 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -717,7 +717,7 @@ static bool __init early_memremap_is_setup_data(resource_size_t phys_addr,
paddr_next = data->next;
len = data->len;

- if ((phys_addr > paddr) && (phys_addr < (paddr + len))) {
+ if ((phys_addr > paddr) && (phys_addr < (paddr + size + len))) {
early_memunmap(data, sizeof(*data));
return true;
}
--
2.41.0