[PATCH v3] EDAC/ghes: Set the DIMM label unconditionally

Toshi Kani
2022-07-26T16:46:53Z

The following buffer overflow BUG was observed on an HPE system.
ghes_edac_register() called strlen() on an uninitialized label,
which had non-zero values from krealloc_array().

detected buffer overflow in __fortify_strlen
------------[ cut here ]------------
kernel BUG at lib/string_helpers.c:983!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 1 PID: 1 Comm: swapper/0 Tainted: G I 5.18.6-200.fc36.x86_64 #1
Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/15/2019
RIP: 0010:fortify_panic
...
Call Trace:
<TASK>
ghes_edac_register.cold
ghes_probe
platform_probe
really_probe
__driver_probe_device
driver_probe_device
__driver_attach
? __device_attach_driver
bus_for_each_dev
bus_add_driver
driver_register
acpi_ghes_init
acpi_init
? acpi_sleep_proc_init
do_one_initcall

dimm_setup_label() only initializes the label when both bank and
device are set. This HPE BIOS only sets device since bank locator
is unnecessary to locate a DIMM.

Handle 0x0020, DMI type 17, 84 bytes
Memory Device
Array Handle: 0x0013
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: 32 GB
Form Factor: DIMM
Set: None
Locator: PROC 1 DIMM 1 <=== device
Bank Locator: Not Specified <=== bank

Change dimm_setup_label() to always initialize the label to fix the
issue. It sets to a null string in case BIOS does not provide both
bank and device so that ghes_edac_register() keeps the default label
from edac_mc_alloc_dimms().

Fixes: b9cae27728d1f ("EDAC/ghes: Scan the system once on driver init")
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Co-developed-by: Robert Richter <rric@kernel.org>
Tested-by: Robert Elliott <elliott@hpe.com>
---
drivers/edac/ghes_edac.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index 59b0bedc9c24..c229ed0ce678 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -103,9 +103,15 @@ static void dimm_setup_label(struct dimm_info *dimm, u16 handle)

dmi_memdev_name(handle, &bank, &device);

- /* both strings must be non-zero */
- if (bank && *bank && device && *device)
- snprintf(dimm->label, sizeof(dimm->label), "%s %s", bank, device);
+ /*
+ * Set a null string when both bank and device are zero.
+ * This keeps ghes_edac_register() preserving the default
+ * label from edac_mc_alloc_dimms().
+ */
+ snprintf(dimm->label, sizeof(dimm->label), "%s%s%s",
+ (bank && *bank) ? bank : "",
+ (bank && *bank && device && *device) ? " " : "",
+ (device && *device) ? device : "");
}

static void assign_dmi_dimm_info(struct dimm_info *dimm, struct memdev_dmi_entry *entry)