[PATCH 6.18 054/752] EFI/CPER: don't go past the ARM processor CPER record buffer

Sasha Levin
2026-02-28T17:48:54Z

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

[ Upstream commit eae21beecb95a3b69ee5c38a659f774e171d730e ]

There's a logic inside GHES/CPER to detect if the section_length
is too small, but it doesn't detect if it is too big.

Currently, if the firmware receives an ARM processor CPER record
stating that a section length is big, kernel will blindly trust
section_length, producing a very long dump. For instance, a 67
bytes record with ERR_INFO_NUM set 46198 and section length
set to 854918320 would dump a lot of data going a way past the
firmware memory-mapped area.

Fix it by adding a logic to prevent it to go past the buffer
if ERR_INFO_NUM is too big, making it report instead:

[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1
[Hardware Error]: event severity: recoverable
[Hardware Error]: Error 0, type: recoverable
[Hardware Error]: section_type: ARM processor error
[Hardware Error]: MIDR: 0xff304b2f8476870a
[Hardware Error]: section length: 854918320, CPER size: 67
[Hardware Error]: section length is too big
[Hardware Error]: firmware-generated error record is incorrect
[Hardware Error]: ERR_INFO_NUM is 46198

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 and changelog tweaks ]
Link: https://patch.msgid.link/41cd9f6b3ace3cdff7a5e864890849e4b1c58b63.1767871950.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/firmware/efi/cper-arm.c | 12 ++++++++----
drivers/firmware/efi/cper.c | 3 ++-
include/linux/cper.h | 3 ++-
3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/efi/cper-arm.c b/drivers/firmware/efi/cper-arm.c
index 76542a53e2027..b21cb1232d820 100644
--- a/drivers/firmware/efi/cper-arm.c
+++ b/drivers/firmware/efi/cper-arm.c
@@ -226,7 +226,8 @@ static void cper_print_arm_err_info(const char *pfx, u32 type,
}

void cper_print_proc_arm(const char *pfx,
- const struct cper_sec_proc_arm *proc)
+ const struct cper_sec_proc_arm *proc,
+ u32 length)
{
int i, len, max_ctx_type;
struct cper_arm_err_info *err_info;
@@ -238,9 +239,12 @@ void cper_print_proc_arm(const char *pfx,

len = proc->section_length - (sizeof(*proc) +
proc->err_info_num * (sizeof(*err_info)));
- if (len < 0) {
- printk("%ssection length: %d\n", pfx, proc->section_length);
- printk("%ssection length is too small\n", pfx);
+
+ if (len < 0 || proc->section_length > length) {
+ printk("%ssection length: %d, CPER size: %d\n",
+ pfx, proc->section_length, length);
+ printk("%ssection length is too %s\n", pfx,
+ (len < 0) ? "small" : "big");
printk("%sfirmware-generated error record is incorrect\n", pfx);
printk("%sERR_INFO_NUM is %d\n", pfx, proc->err_info_num);
return;
diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index d58ff956a699c..d4dc69693ece4 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -664,7 +664,8 @@ cper_estatus_print_section(const char *pfx, struct acpi_hest_generic_data *gdata

printk("%ssection_type: ARM processor error\n", newpfx);
if (gdata->error_data_length >= sizeof(*arm_err))
- cper_print_proc_arm(newpfx, arm_err);
+ cper_print_proc_arm(newpfx, arm_err,
+ gdata->error_data_length);
else
goto err_section_too_small;
#endif
diff --git a/include/linux/cper.h b/include/linux/cper.h
index 5b1236d8c65bb..440b35e459e53 100644
--- a/include/linux/cper.h
+++ b/include/linux/cper.h
@@ -595,7 +595,8 @@ void cper_mem_err_pack(const struct cper_sec_mem_err *,
const char *cper_mem_err_unpack(struct trace_seq *,
struct cper_mem_err_compact *);
void cper_print_proc_arm(const char *pfx,
- const struct cper_sec_proc_arm *proc);
+ const struct cper_sec_proc_arm *proc,
+ u32 length);
void cper_print_proc_ia(const char *pfx,
const struct cper_sec_proc_ia *proc);
int cper_mem_err_location(struct cper_mem_err_compact *mem, char *msg);
--
2.51.0