[PATCH v4 0/4] apei/ghes: don't OOPS with bad ARM error CPER records

[PATCH v4 0/4] apei/ghes: don't OOPS with bad ARM error CPER records

[Mauro Carvalho Chehab]

Rafael,

Current parsing logic at apei/ghes for ARM Processor Error
assumes that the record sizes are correct. Yet, a bad BIOS
might produce malformed GHES reports.

Worse than that, it may end exposing data from other memory
addresses, as the logic may end dumping large portions of
the memory.

Avoid that by checking the buffer sizes where needed.

---

v4:
 - addressed Jonathan comments;
 - added two extra patches to prevent other OOM issues.

v3:
  - addressed Shuai feedback;
  - moved all ghes code to one patch;
  - fixed a typo and a bad indent;
  - cleanup the size check logic at ghes.c.


Mauro Carvalho Chehab (4):
  apei/ghes: ARM processor Error: don't go past allocated memory
  efi/cper: don't go past the ARM processor CPER record buffer
  apei/ghes: ensure that won't go past CPER allocated record
  efi/cper: don't dump the entire memory region

 drivers/acpi/apei/ghes.c        | 38 ++++++++++++++++++++++++++++-----
 drivers/firmware/efi/cper-arm.c | 12 +++++++----
 drivers/firmware/efi/cper.c     |  8 ++++++-
 drivers/ras/ras.c               |  6 +++++-
 include/acpi/ghes.h             |  1 +
 include/linux/cper.h            |  3 ++-
 6 files changed, 56 insertions(+), 12 deletions(-)

-- 
2.52.0

[PATCH v4 1/4] apei/ghes: ARM processor Error: don't go past allocated memory

[Mauro Carvalho Chehab]

If the BIOS generates a very small ARM Processor Error, or
an incomplete one, the current logic will fail to deferrence

	err->section_length
and
	ctx_info->size

Add checks to avoid that. With such changes, such GHESv2
records won't cause OOPSes like this:

[    1.492129] Internal error: Oops: 0000000096000005 [#1]  SMP
[    1.495449] Modules linked in:
[    1.495820] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.18.0-rc1-00017-gabadcc3553dd-dirty #18 PREEMPT
[    1.496125] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 02/02/2022
[    1.496433] Workqueue: kacpi_notify acpi_os_execute_deferred
[    1.496967] pstate: 814000c5 (Nzcv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[    1.497199] pc : log_arm_hw_error+0x5c/0x200
[    1.497380] lr : ghes_handle_arm_hw_error+0x94/0x220

0xffff8000811c5324 is in log_arm_hw_error (../drivers/ras/ras.c:75).
70		err_info = (struct cper_arm_err_info *)(err + 1);
71		ctx_info = (struct cper_arm_ctx_info *)(err_info + err->err_info_num);
72		ctx_err = (u8 *)ctx_info;
73
74		for (n = 0; n < err->context_info_num; n++) {
75			sz = sizeof(struct cper_arm_ctx_info) + ctx_info->size;
76			ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);
77			ctx_len += sz;
78		}
79

and similar ones while trying to access section_length on an
error dump with too small size.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 drivers/acpi/apei/ghes.c | 32 ++++++++++++++++++++++++++++----
 drivers/ras/ras.c        |  6 +++++-
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 0dc767392a6c..fc3f8aed99d5 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -552,21 +552,45 @@ static bool ghes_handle_arm_hw_error(struct acpi_hest_generic_data *gdata,
 {
 	struct cper_sec_proc_arm *err = acpi_hest_get_payload(gdata);
 	int flags = sync ? MF_ACTION_REQUIRED : 0;
+	int length = gdata->error_data_length;
 	char error_type[120];
 	bool queued = false;
 	int sec_sev, i;
 	char *p;
 
 	sec_sev = ghes_severity(gdata->error_severity);
-	log_arm_hw_error(err, sec_sev);
+	if (length >= sizeof(*err)) {
+		log_arm_hw_error(err, sec_sev);
+	} else {
+		pr_warn(FW_BUG "arm error length: %d\n", length);
+		pr_warn(FW_BUG "length is too small\n");
+		pr_warn(FW_BUG "firmware-generated error record is incorrect\n");
+		return false;
+	}
+
 	if (sev != GHES_SEV_RECOVERABLE || sec_sev != GHES_SEV_RECOVERABLE)
 		return false;
 
 	p = (char *)(err + 1);
+	length -= sizeof(err);
+
 	for (i = 0; i < err->err_info_num; i++) {
-		struct cper_arm_err_info *err_info = (struct cper_arm_err_info *)p;
-		bool is_cache = err_info->type & CPER_ARM_CACHE_ERROR;
-		bool has_pa = (err_info->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR);
+		struct cper_arm_err_info *err_info;
+		bool is_cache, has_pa;
+
+		/* Ensure we have enough data for the error info header */
+		if (length < sizeof(*err_info))
+			break;
+
+		err_info = (struct cper_arm_err_info *)p;
+
+		/* Validate the claimed length before using it */
+		length -= err_info->length;
+		if (length < 0)
+			break;
+
+		is_cache = err_info->type & CPER_ARM_CACHE_ERROR;
+		has_pa = (err_info->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR);
 
 		/*
 		 * The field (err_info->error_info & BIT(26)) is fixed to set to
diff --git a/drivers/ras/ras.c b/drivers/ras/ras.c
index 2a5b5a9fdcb3..03df3db62334 100644
--- a/drivers/ras/ras.c
+++ b/drivers/ras/ras.c
@@ -72,7 +72,11 @@ void log_arm_hw_error(struct cper_sec_proc_arm *err, const u8 sev)
 	ctx_err = (u8 *)ctx_info;
 
 	for (n = 0; n < err->context_info_num; n++) {
-		sz = sizeof(struct cper_arm_ctx_info) + ctx_info->size;
+		sz = sizeof(struct cper_arm_ctx_info);
+
+		if (sz + (long)ctx_info - (long)err >= err->section_length)
+			sz += ctx_info->size;
+
 		ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);
 		ctx_len += sz;
 	}
-- 
2.52.0

Re: [PATCH v4 1/4] apei/ghes: ARM processor Error: don't go past allocated memory

[Jonathan Cameron]

On Tue,  6 Jan 2026 11:01:35 +0100
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

> If the BIOS generates a very small ARM Processor Error, or
> an incomplete one, the current logic will fail to deferrence
> 
> 	err->section_length
> and
> 	ctx_info->size
> 
> Add checks to avoid that. With such changes, such GHESv2
> records won't cause OOPSes like this:
> 
> [    1.492129] Internal error: Oops: 0000000096000005 [#1]  SMP
> [    1.495449] Modules linked in:
> [    1.495820] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.18.0-rc1-00017-gabadcc3553dd-dirty #18 PREEMPT
> [    1.496125] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 02/02/2022
> [    1.496433] Workqueue: kacpi_notify acpi_os_execute_deferred
> [    1.496967] pstate: 814000c5 (Nzcv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
> [    1.497199] pc : log_arm_hw_error+0x5c/0x200
> [    1.497380] lr : ghes_handle_arm_hw_error+0x94/0x220
> 
> 0xffff8000811c5324 is in log_arm_hw_error (../drivers/ras/ras.c:75).
> 70		err_info = (struct cper_arm_err_info *)(err + 1);
> 71		ctx_info = (struct cper_arm_ctx_info *)(err_info + err->err_info_num);
> 72		ctx_err = (u8 *)ctx_info;
> 73
> 74		for (n = 0; n < err->context_info_num; n++) {
> 75			sz = sizeof(struct cper_arm_ctx_info) + ctx_info->size;
> 76			ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);
> 77			ctx_len += sz;
> 78		}
> 79
> 
> and similar ones while trying to access section_length on an
> error dump with too small size.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Hi Mauro,

Resolved the stuff I pointed out in previous, so LGTM.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>