[PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[Toshi Kani]

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().
Change dimm_setup_label() to always initialize the label.

 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+0xf/0x11
 ...
 Call Trace:
  <TASK>
  ghes_edac_register.cold+0x128/0x128
  ghes_probe+0x142/0x3a0
  platform_probe+0x41/0x90
  really_probe+0x19e/0x370
  __driver_probe_device+0xfc/0x170
  driver_probe_device+0x1f/0x90
  __driver_attach+0xbb/0x190
  ? __device_attach_driver+0xe0/0xe0
  bus_for_each_dev+0x5f/0x90
  bus_add_driver+0x159/0x200
  driver_register+0x89/0xd0
  acpi_ghes_init+0x72/0xc3
  acpi_init+0x441/0x493
  ? acpi_sleep_proc_init+0x24/0x24
  do_one_initcall+0x41/0x200

Fixes: b9cae27728d1f ("EDAC/ghes: Scan the system once on driver init")
Tested-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Robert Richter <rrichter@marvell.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/edac/ghes_edac.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index 59b0bedc9c24..3ad3d5fc45e0 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -106,6 +106,8 @@ static void dimm_setup_label(struct dimm_info *dimm, u16 handle)
 	/* both strings must be non-zero */
 	if (bank && *bank && device && *device)
 		snprintf(dimm->label, sizeof(dimm->label), "%s %s", bank, device);
+	else
+		dimm->label[0] = '\0';
 }
 
 static void assign_dmi_dimm_info(struct dimm_info *dimm, struct memdev_dmi_entry *entry)

Re: [PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[Borislav Petkov]

On Tue, Jul 19, 2022 at 04:01:24PM -0600, Toshi Kani wrote:
> 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().
> Change dimm_setup_label() to always initialize the label.

Do we also know why dmi_memdev_name() doesn't give bank and/or device?

SMBIOS handle wrong?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

RE: [PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[Kani, Toshi]

Borislav Petkov wrote:
> On Tue, Jul 19, 2022 at 04:01:24PM -0600, Toshi Kani wrote:
> > 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().
> > Change dimm_setup_label() to always initialize the label.
>
> Do we also know why dmi_memdev_name() doesn't give bank and/or device?

Yes.

> SMBIOS handle wrong?

SMBIOS handle is correct.

In dimm_setup_label(), *device is set but *bank is null (dmi_empty_string).
*bank is set from SMBIOS type 17 Bank Locator, offset 11h.  This value is
set to 0x0 (null string) on this system, as shown below.

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
        ....

Handle 0x0020, DMI type 17, 84 bytes
        Header and Data:
                11 54 20 00 13 00 FE FF 48 00 40 00 FF 7F 09 00
                01 00 1A 80 20 75 0B 02 00 00 03 02 00 80 00 00
                   ^^
                75 0B B0 04 B0 04 B0 04 03 08 00 00 89 83 00 00
                00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                00 00 00 00
        Strings:
                50 52 4F 43 20 31 20 44 49 4D 4D 20 31 00
                PROC 1 DIMM 1
                55 4E 4B 4E 4F 57 4E 00
                UNKNOWN
                4E 4F 54 20 41 56 41 49 4C 41 42 4C 45 00
                NOT AVAILABLE

Thanks,
Toshi

Re: [PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[Borislav Petkov]

On Wed, Jul 20, 2022 at 03:41:20PM +0000, Kani, Toshi wrote:
> SMBIOS handle is correct.
> 
> In dimm_setup_label(), *device is set but *bank is null (dmi_empty_string).
> *bank is set from SMBIOS type 17 Bank Locator, offset 11h.  This value is
> set to 0x0 (null string) on this system, as shown below.
> 
> 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

I think it'll be more user-friendly to put

"PROC 1 DIMM 1" for device

and

"NA" or so for bank

instead of setting the label to the NULL string.

I.e., relax that

	if (bank && *bank && device && *device)

check there.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

RE: [PATCH] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

[Kani, Toshi]

Borislav Petkov wrote:
> I think it'll be more user-friendly to put
>
> "PROC 1 DIMM 1" for device
>
> and
>
> "NA" or so for bank
>
> instead of setting the label to the NULL string.
>
> I.e., relax that
> 
> 	if (bank && *bank && device && *device)
> 
> check there.

Good idea.  I will send a v2 patch to set "NA" in case device or bank
is null.

Thanks,
Toshi