[PATCH 0/1] dmi_scan: uuid: fix endianess for smbios >= 0x206

[PATCH 0/1] dmi_scan: uuid: fix endianess for smbios >= 0x206

[Andrea Arcangeli]

Hello,

this fixes https://bugzilla.kernel.org/show_bug.cgi?id=109731

Without this fix when this code runs:

	if (dmi_ver >= 0x020600)
		sprintf(s, "%pUL", d);
	else
		sprintf(s, "%pUB", d);

dmi_ver is still set to the old 0x20X instead of 0x20X00 as intended
after commit 95be58df74a5b21e5a78e45fddb2fd59112524c5.

Andrea Arcangeli (1):
  dmi_scan: uuid: fix endianess for smbios >= 0x206

 drivers/firmware/dmi_scan.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

[PATCH 1/1] dmi_scan: uuid: fix endianess for smbios >= 0x206

[Andrea Arcangeli]

The dmi_ver wasn't updated correctly before the dmi_decode method run
to save the uuid.

That resulted in "dmidecode -s system-uuid" and
/sys/class/dmi/id/product_uuid disagreeing. The latter was buggy and
this fixes it.

Reported-by: Federico Simoncelli <fsimonce@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
 drivers/firmware/dmi_scan.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index ac1ce4a..0e08e66 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -521,6 +521,7 @@ static int __init dmi_present(const u8 *buf)
 			dmi_ver = smbios_ver;
 		else
 			dmi_ver = (buf[14] & 0xF0) << 4 | (buf[14] & 0x0F);
+		dmi_ver <<= 8;
 		dmi_num = get_unaligned_le16(buf + 12);
 		dmi_len = get_unaligned_le16(buf + 6);
 		dmi_base = get_unaligned_le32(buf + 8);
@@ -528,15 +529,14 @@ static int __init dmi_present(const u8 *buf)
 		if (dmi_walk_early(dmi_decode) == 0) {
 			if (smbios_ver) {
 				pr_info("SMBIOS %d.%d present.\n",
-				       dmi_ver >> 8, dmi_ver & 0xFF);
+					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
 			} else {
 				smbios_entry_point_size = 15;
 				memcpy(smbios_entry_point, buf,
 				       smbios_entry_point_size);
 				pr_info("Legacy DMI %d.%d present.\n",
-				       dmi_ver >> 8, dmi_ver & 0xFF);
+					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
 			}
-			dmi_ver <<= 8;
 			dmi_format_ids(dmi_ids_string, sizeof(dmi_ids_string));
 			printk(KERN_DEBUG "DMI: %s\n", dmi_ids_string);
 			return 0;

Re: [PATCH 1/1] dmi_scan: uuid: fix endianess for smbios >= 0x206

[Matt Fleming]

(Cc'ing Jean since he's the maintainer)

On Tue, 22 Dec, at 02:53:10PM, Andrea Arcangeli wrote:
> The dmi_ver wasn't updated correctly before the dmi_decode method run
> to save the uuid.
> 
> That resulted in "dmidecode -s system-uuid" and
> /sys/class/dmi/id/product_uuid disagreeing. The latter was buggy and
> this fixes it.
> 
> Reported-by: Federico Simoncelli <fsimonce@redhat.com>
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> ---
>  drivers/firmware/dmi_scan.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> index ac1ce4a..0e08e66 100644
> --- a/drivers/firmware/dmi_scan.c
> +++ b/drivers/firmware/dmi_scan.c
> @@ -521,6 +521,7 @@ static int __init dmi_present(const u8 *buf)
>  			dmi_ver = smbios_ver;
>  		else
>  			dmi_ver = (buf[14] & 0xF0) << 4 | (buf[14] & 0x0F);
> +		dmi_ver <<= 8;
>  		dmi_num = get_unaligned_le16(buf + 12);
>  		dmi_len = get_unaligned_le16(buf + 6);
>  		dmi_base = get_unaligned_le32(buf + 8);
> @@ -528,15 +529,14 @@ static int __init dmi_present(const u8 *buf)
>  		if (dmi_walk_early(dmi_decode) == 0) {
>  			if (smbios_ver) {
>  				pr_info("SMBIOS %d.%d present.\n",
> -				       dmi_ver >> 8, dmi_ver & 0xFF);
> +					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
>  			} else {
>  				smbios_entry_point_size = 15;
>  				memcpy(smbios_entry_point, buf,
>  				       smbios_entry_point_size);
>  				pr_info("Legacy DMI %d.%d present.\n",
> -				       dmi_ver >> 8, dmi_ver & 0xFF);
> +					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
>  			}
> -			dmi_ver <<= 8;
>  			dmi_format_ids(dmi_ids_string, sizeof(dmi_ids_string));
>  			printk(KERN_DEBUG "DMI: %s\n", dmi_ids_string);
>  			return 0;

Re: [PATCH 1/1] dmi_scan: uuid: fix endianess for smbios >= 0x206

[Jean Delvare]

Hi Matt, Andrea,

On Tue, 22 Dec 2015 15:17:51 +0000, Matt Fleming wrote:
> (Cc'ing Jean since he's the maintainer)
> 
> On Tue, 22 Dec, at 02:53:10PM, Andrea Arcangeli wrote:
> > The dmi_ver wasn't updated correctly before the dmi_decode method run
> > to save the uuid.
> > 
> > That resulted in "dmidecode -s system-uuid" and
> > /sys/class/dmi/id/product_uuid disagreeing. The latter was buggy and
> > this fixes it.
> > 
> > Reported-by: Federico Simoncelli <fsimonce@redhat.com>
> > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> > ---
> >  drivers/firmware/dmi_scan.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> > index ac1ce4a..0e08e66 100644
> > --- a/drivers/firmware/dmi_scan.c
> > +++ b/drivers/firmware/dmi_scan.c
> > @@ -521,6 +521,7 @@ static int __init dmi_present(const u8 *buf)
> >  			dmi_ver = smbios_ver;
> >  		else
> >  			dmi_ver = (buf[14] & 0xF0) << 4 | (buf[14] & 0x0F);
> > +		dmi_ver <<= 8;
> >  		dmi_num = get_unaligned_le16(buf + 12);
> >  		dmi_len = get_unaligned_le16(buf + 6);
> >  		dmi_base = get_unaligned_le32(buf + 8);
> > @@ -528,15 +529,14 @@ static int __init dmi_present(const u8 *buf)
> >  		if (dmi_walk_early(dmi_decode) == 0) {
> >  			if (smbios_ver) {
> >  				pr_info("SMBIOS %d.%d present.\n",
> > -				       dmi_ver >> 8, dmi_ver & 0xFF);
> > +					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
> >  			} else {
> >  				smbios_entry_point_size = 15;
> >  				memcpy(smbios_entry_point, buf,
> >  				       smbios_entry_point_size);
> >  				pr_info("Legacy DMI %d.%d present.\n",
> > -				       dmi_ver >> 8, dmi_ver & 0xFF);
> > +					dmi_ver >> 16, (dmi_ver >> 8) & 0xFF);
> >  			}
> > -			dmi_ver <<= 8;
> >  			dmi_format_ids(dmi_ids_string, sizeof(dmi_ids_string));
> >  			printk(KERN_DEBUG "DMI: %s\n", dmi_ids_string);
> >  			return 0;

Baaah. This was supposed to be fixed by my commit
5c1ac56b51b9d222ab202dec1ac2f4215346129d ("firmware: dmi_scan: Fix
ordering of product_uuid") but clearly I missed half of the required
changes. Should have tested...

The irony is that I clearly remember when reviewing Ivan's patches that
I did not like this part of the code. Quoting myself:

"I understand this was the easiest way to implement the change, but I'm
not really comfortable with dmi_ver having different formats for
different parts of the code. This is rather error prone for future
changes, even if the code is currently correct."

Even though I was wrong when claiming that the code was "currently
correct", I should have listened to my gut feeling back then and asked
for a different implementation.

Anyway... Thanks Andrea, applied with the missing "Fixes:" markers
added. I'll send to Linus soon.

-- 
Jean Delvare
SUSE L3 Support