[PATCH 6.18 052/752] APEI/GHES: ensure that won't go past CPER allocated record

Sasha Levin
2026-02-28T17:48:52Z

From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

[ Upstream commit fa2408a24f8f0db14d9cfc613ef162dc267d7ad4 ]

The logic at ghes_new() prevents allocating too large records, by
checking if they're bigger than GHES_ESTATUS_MAX_SIZE (currently, 64KB).
Yet, the allocation is done with the actual number of pages from the
CPER bios table location, which can be smaller.

Yet, a bad firmware could send data with a different size, which might
be bigger than the allocated memory, causing an OOPS:

Unable to handle kernel paging request at virtual address fff00000f9b40000
Mem abort info:
ESR = 0x0000000096000007
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x07: level 3 translation fault
Data abort info:
ISV = 0, ISS = 0x00000007, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
swapper pgtable: 4k pages, 52-bit VAs, pgdp=000000008ba16000
[fff00000f9b40000] pgd=180000013ffff403, p4d=180000013fffe403, pud=180000013f85b403, pmd=180000013f68d403, pte=0000000000000000
Internal error: Oops: 0000000096000007 [#1] SMP
Modules linked in:
CPU: 0 UID: 0 PID: 303 Comm: kworker/0:1 Not tainted 6.19.0-rc1-00002-gda407d200220 #34 PREEMPT
Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 02/02/2022
Workqueue: kacpi_notify acpi_os_execute_deferred
pstate: 214020c5 (nzCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : hex_dump_to_buffer+0x30c/0x4a0
lr : hex_dump_to_buffer+0x328/0x4a0
sp : ffff800080e13880
x29: ffff800080e13880 x28: ffffac9aba86f6a8 x27: 0000000000000083
x26: fff00000f9b3fffc x25: 0000000000000004 x24: 0000000000000004
x23: ffff800080e13905 x22: 0000000000000010 x21: 0000000000000083
x20: 0000000000000001 x19: 0000000000000008 x18: 0000000000000010
x17: 0000000000000001 x16: 00000007c7f20fec x15: 0000000000000020
x14: 0000000000000008 x13: 0000000000081020 x12: 0000000000000008
x11: ffff800080e13905 x10: ffff800080e13988 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000001 x6 : 0000000000000020
x5 : 0000000000000030 x4 : 00000000fffffffe x3 : 0000000000000000
x2 : ffffac9aba78c1c8 x1 : ffffac9aba76d0a8 x0 : 0000000000000008
Call trace:
hex_dump_to_buffer+0x30c/0x4a0 (P)
print_hex_dump+0xac/0x170
cper_estatus_print_section+0x90c/0x968
cper_estatus_print+0xf0/0x158
__ghes_print_estatus+0xa0/0x148
ghes_proc+0x1bc/0x220
ghes_notify_hed+0x5c/0xb8
notifier_call_chain+0x78/0x148
blocking_notifier_call_chain+0x4c/0x80
acpi_hed_notify+0x28/0x40
acpi_ev_notify_dispatch+0x50/0x80
acpi_os_execute_deferred+0x24/0x48
process_one_work+0x15c/0x3b0
worker_thread+0x2d0/0x400
kthread+0x148/0x228
ret_from_fork+0x10/0x20
Code: 6b14033f 540001ad a94707e2 f100029f (b8747b44)
---[ end trace 0000000000000000 ]---

Prevent that by taking the actual allocated are into account when
checking for CPER length.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
[ rjw: Subject tweaks ]
Link: https://patch.msgid.link/4e70310a816577fabf37d94ed36cde4ad62b1e0a.1767871950.git.mchehab+huawei@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/apei/ghes.c | 6 +++++-
include/acpi/ghes.h | 1 +
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 56107aa002744..1b34a708e98a4 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -29,6 +29,7 @@
#include <linux/cper.h>
#include <linux/cleanup.h>
#include <linux/platform_device.h>
+#include <linux/minmax.h>
#include <linux/mutex.h>
#include <linux/ratelimit.h>
#include <linux/vmalloc.h>
@@ -293,6 +294,7 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
error_block_length = GHES_ESTATUS_MAX_SIZE;
}
ghes->estatus = kmalloc(error_block_length, GFP_KERNEL);
+ ghes->estatus_length = error_block_length;
if (!ghes->estatus) {
rc = -ENOMEM;
goto err_unmap_status_addr;
@@ -364,13 +366,15 @@ static int __ghes_check_estatus(struct ghes *ghes,
struct acpi_hest_generic_status *estatus)
{
u32 len = cper_estatus_len(estatus);
+ u32 max_len = min(ghes->generic->error_block_length,
+ ghes->estatus_length);

if (len < sizeof(*estatus)) {
pr_warn_ratelimited(FW_WARN GHES_PFX "Truncated error status block!\n");
return -EIO;
}

- if (len > ghes->generic->error_block_length) {
+ if (!len || len > max_len) {
pr_warn_ratelimited(FW_WARN GHES_PFX "Invalid error status block length!\n");
return -EIO;
}
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index ebd21b05fe6ed..93db60da5934e 100644
--- a/include/acpi/ghes.h
+++ b/include/acpi/ghes.h
@@ -21,6 +21,7 @@ struct ghes {
struct acpi_hest_generic_v2 *generic_v2;
};
struct acpi_hest_generic_status *estatus;
+ unsigned int estatus_length;
unsigned long flags;
union {
struct list_head list;
--
2.51.0