diff mbox series

slof/fs/packages/disk-label.fs: improve checking for DOS boot partitions

Message ID 20240222061046.42572-1-kconsul@linux.vnet.ibm.com
State Superseded
Headers show
Series slof/fs/packages/disk-label.fs: improve checking for DOS boot partitions | expand

Commit Message

Kautuk Consul Feb. 22, 2024, 6:10 a.m. UTC
While testing with a qcow2 with a DOS boot partition it was found that
when we set the logical_block_size in the guest XML to >512 then the
boot would fail in the following interminable loop:
<SNIP>
Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
</SNIP>

Change the count-dos-logical-partitions Forth subroutine and the Forth
subroutines calling count-dos-logical-partitions to check for this access
beyond end of device error.

After making the above changes, it fails properly with the correct error
message as follows:
<SNIP>
Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!
virtioblk_transfer: Access beyond end of device!

E3404: Not a bootable device!

E3407: Load failed

  Type 'boot' and press return to continue booting the system.
  Type 'reset-all' and press return to reboot the system.

Ready!
0 >
</SNIP>

Signed-off-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
---
 slof/fs/packages/disk-label.fs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Comments

Kautuk Consul March 7, 2024, 6:35 a.m. UTC | #1
Hi,

On 2024-02-22 01:10:46, Kautuk Consul wrote:
> While testing with a qcow2 with a DOS boot partition it was found that
> when we set the logical_block_size in the guest XML to >512 then the
> boot would fail in the following interminable loop:
> <SNIP>
> Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> </SNIP>
> 
> Change the count-dos-logical-partitions Forth subroutine and the Forth
> subroutines calling count-dos-logical-partitions to check for this access
> beyond end of device error.
> 
> After making the above changes, it fails properly with the correct error
> message as follows:
> <SNIP>
> Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> virtioblk_transfer: Access beyond end of device!
> 
> E3404: Not a bootable device!
> 
> E3407: Load failed
> 
>   Type 'boot' and press return to continue booting the system.
>   Type 'reset-all' and press return to reboot the system.
> 
> Ready!
> 0 >
> </SNIP>
> 
> Signed-off-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
> ---
>  slof/fs/packages/disk-label.fs | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
> index 661c6b0..e680847 100644
> --- a/slof/fs/packages/disk-label.fs
> +++ b/slof/fs/packages/disk-label.fs
> @@ -139,6 +139,13 @@ CONSTANT /gpt-part-entry
>     block block-size read drop    \ read sector
>  ;
> 
> +\ read sector to array "block" and return actual bytes read
> +: read-sector-ret ( sector-number -- actual)
> +   \ block-size is 0x200 on disks, 0x800 on cdrom drives
> +   block-size * 0 seek drop      \ seek to sector
> +   block block-size read    \ read sector
> +;
> +
>  : (.part-entry) ( part-entry )
>     cr ." part-entry>active:        " dup part-entry>active c@ .d
>     cr ." part-entry>start-head:    " dup part-entry>start-head c@ .d
> @@ -204,7 +211,8 @@ CONSTANT /gpt-part-entry
>           part-entry>sector-offset l@-le    ( current sector )
>           dup to part-start to lpart-start  ( current )
>           BEGIN
> -            part-start read-sector          \ read EBR
> +            part-start read-sector-ret          \ read EBR
> +            block-size < IF UNLOOP 0 EXIT THEN
>              1 partition>start-sector IF
>                 \ ." Logical Partition found at " part-start .d cr
>                 1+
> @@ -279,6 +287,7 @@ CONSTANT /gpt-part-entry
>     THEN
> 
>     count-dos-logical-partitions TO dos-logical-partitions
> +   dos-logical-partitions 0= IF false EXIT THEN
> 
>     debug-disk-label? IF
>        ." Found " dos-logical-partitions .d ." logical partitions" cr
> @@ -352,6 +361,7 @@ CONSTANT /gpt-part-entry
>     no-mbr? IF drop FALSE EXIT THEN  \ read MBR and check for DOS disk-label magic
> 
>     count-dos-logical-partitions TO dos-logical-partitions
> +   dos-logical-partitions 0= IF 0 EXIT THEN
> 
>     debug-disk-label? IF
>        ." Found " dos-logical-partitions .d ." logical partitions" cr
> -- 
> 2.31.1
> 

So how does the patch look ? Any comments ?
Kautuk Consul March 18, 2024, 5:14 a.m. UTC | #2
Hi,
> 
> On 2024-02-22 01:10:46, Kautuk Consul wrote:
> > While testing with a qcow2 with a DOS boot partition it was found that
> > when we set the logical_block_size in the guest XML to >512 then the
> > boot would fail in the following interminable loop:
> > <SNIP>
> > Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > </SNIP>
> > 
> > Change the count-dos-logical-partitions Forth subroutine and the Forth
> > subroutines calling count-dos-logical-partitions to check for this access
> > beyond end of device error.
> > 
> > After making the above changes, it fails properly with the correct error
> > message as follows:
> > <SNIP>
> > Trying to load:  from: /pci@800000020000000/scsi@3 ... virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > virtioblk_transfer: Access beyond end of device!
> > 
> > E3404: Not a bootable device!
> > 
> > E3407: Load failed
> > 
> >   Type 'boot' and press return to continue booting the system.
> >   Type 'reset-all' and press return to reboot the system.
> > 
> > Ready!
> > 0 >
> > </SNIP>
> > 
> > Signed-off-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
> > ---
> >  slof/fs/packages/disk-label.fs | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
> > index 661c6b0..e680847 100644
> > --- a/slof/fs/packages/disk-label.fs
> > +++ b/slof/fs/packages/disk-label.fs
> > @@ -139,6 +139,13 @@ CONSTANT /gpt-part-entry
> >     block block-size read drop    \ read sector
> >  ;
> > 
> > +\ read sector to array "block" and return actual bytes read
> > +: read-sector-ret ( sector-number -- actual)
> > +   \ block-size is 0x200 on disks, 0x800 on cdrom drives
> > +   block-size * 0 seek drop      \ seek to sector
> > +   block block-size read    \ read sector
> > +;
> > +
> >  : (.part-entry) ( part-entry )
> >     cr ." part-entry>active:        " dup part-entry>active c@ .d
> >     cr ." part-entry>start-head:    " dup part-entry>start-head c@ .d
> > @@ -204,7 +211,8 @@ CONSTANT /gpt-part-entry
> >           part-entry>sector-offset l@-le    ( current sector )
> >           dup to part-start to lpart-start  ( current )
> >           BEGIN
> > -            part-start read-sector          \ read EBR
> > +            part-start read-sector-ret          \ read EBR
> > +            block-size < IF UNLOOP 0 EXIT THEN
> >              1 partition>start-sector IF
> >                 \ ." Logical Partition found at " part-start .d cr
> >                 1+
> > @@ -279,6 +287,7 @@ CONSTANT /gpt-part-entry
> >     THEN
> > 
> >     count-dos-logical-partitions TO dos-logical-partitions
> > +   dos-logical-partitions 0= IF false EXIT THEN
> > 
> >     debug-disk-label? IF
> >        ." Found " dos-logical-partitions .d ." logical partitions" cr
> > @@ -352,6 +361,7 @@ CONSTANT /gpt-part-entry
> >     no-mbr? IF drop FALSE EXIT THEN  \ read MBR and check for DOS disk-label magic
> > 
> >     count-dos-logical-partitions TO dos-logical-partitions
> > +   dos-logical-partitions 0= IF 0 EXIT THEN
> > 
> >     debug-disk-label? IF
> >        ." Found " dos-logical-partitions .d ." logical partitions" cr
> > -- 
> > 2.31.1
> > 

So how does the patch look ? Any comments from anyone ?
Thomas Huth March 18, 2024, 10:12 a.m. UTC | #3
On 18/03/2024 06.14, Kautuk Consul wrote:
> Hi,
>>
>> On 2024-02-22 01:10:46, Kautuk Consul wrote:
>>> While testing with a qcow2 with a DOS boot partition it was found that
>>> when we set the logical_block_size in the guest XML to >512 then the
>>> boot would fail
...
>>> diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
>>> index 661c6b0..e680847 100644
>>> --- a/slof/fs/packages/disk-label.fs
>>> +++ b/slof/fs/packages/disk-label.fs
>>> @@ -139,6 +139,13 @@ CONSTANT /gpt-part-entry
>>>      block block-size read drop    \ read sector
>>>   ;
>>>
>>> +\ read sector to array "block" and return actual bytes read
>>> +: read-sector-ret ( sector-number -- actual)

Please add a space between "actual" and ")". I'd maybe also rather say 
"actual-bytes" so that nobody expects "actual-sectors" here.

>>> +   \ block-size is 0x200 on disks, 0x800 on cdrom drives
>>> +   block-size * 0 seek drop      \ seek to sector
>>> +   block block-size read    \ read sector
>>> +;

Could we please avoid duplicating code here? "read-sector" could now simply 
be implemented via read-sector-ret instead:

\ read sector to array "block" and return actual bytes read
: read-sector-ret ( sector-number -- actual-bytes )
     \ block-size is 0x200 on disks, 0x800 on cdrom drives
     block-size * 0 seek drop    \ seek to sector
     block block-size read       \ read sector
;

: read-sector ( sector-number -- )
     read-sector-ret drop
;

>>>   : (.part-entry) ( part-entry )
>>>      cr ." part-entry>active:        " dup part-entry>active c@ .d
>>>      cr ." part-entry>start-head:    " dup part-entry>start-head c@ .d
>>> @@ -204,7 +211,8 @@ CONSTANT /gpt-part-entry
>>>            part-entry>sector-offset l@-le    ( current sector )
>>>            dup to part-start to lpart-start  ( current )
>>>            BEGIN
>>> -            part-start read-sector          \ read EBR
>>> +            part-start read-sector-ret          \ read EBR
>>> +            block-size < IF UNLOOP 0 EXIT THEN
>>>               1 partition>start-sector IF
>>>                  \ ." Logical Partition found at " part-start .d cr
>>>                  1+
>>> @@ -279,6 +287,7 @@ CONSTANT /gpt-part-entry
>>>      THEN
>>>
>>>      count-dos-logical-partitions TO dos-logical-partitions
>>> +   dos-logical-partitions 0= IF false EXIT THEN
>>>
>>>      debug-disk-label? IF
>>>         ." Found " dos-logical-partitions .d ." logical partitions" cr
>>> @@ -352,6 +361,7 @@ CONSTANT /gpt-part-entry
>>>      no-mbr? IF drop FALSE EXIT THEN  \ read MBR and check for DOS disk-label magic
>>>
>>>      count-dos-logical-partitions TO dos-logical-partitions
>>> +   dos-logical-partitions 0= IF 0 EXIT THEN
>>>
>>>      debug-disk-label? IF
>>>         ." Found " dos-logical-partitions .d ." logical partitions" cr
>>> -- 
>>> 2.31.1
>>>
> 
> So how does the patch look ? Any comments from anyone ?

Sorry, your original patch somehow didn't make it to my Inbox (though it's 
visible on http://patchwork.ozlabs.org/project/slof/list/ so the problem is 
certainly on my receiving side), so I just learnt about this patch today.

Anyway, apart from the code duplication, it looks fine to me, so if you 
could fix that in a v2, that would be great!

  Thomas
Alexey Kardashevskiy April 4, 2024, 12:44 a.m. UTC | #4
On Mon, 18 Mar 2024, at 21:12, Thomas Huth wrote:

> Sorry, your original patch somehow didn't make it to my Inbox (though it's 
> visible on http://patchwork.ozlabs.org/project/slof/list/ so the problem is 
> certainly on my receiving side), so I just learnt about this patch today.

Not so sure, there are/were some oddities with it, see - patworks did not pick any response expect from Kautuk:

https://patchwork.ozlabs.org/project/slof/patch/20240202051548.877087-1-kconsul@linux.vnet.ibm.com/

Then I tweaked the mailman so may be it is fixed now. Thanks,

ps. I disagree about that "+COMP and -COMP" guy  as it is not making anything "more informative" as it is hardly ever possible with SLOF but it is a different story :)
diff mbox series

Patch

diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
index 661c6b0..e680847 100644
--- a/slof/fs/packages/disk-label.fs
+++ b/slof/fs/packages/disk-label.fs
@@ -139,6 +139,13 @@  CONSTANT /gpt-part-entry
    block block-size read drop    \ read sector
 ;
 
+\ read sector to array "block" and return actual bytes read
+: read-sector-ret ( sector-number -- actual)
+   \ block-size is 0x200 on disks, 0x800 on cdrom drives
+   block-size * 0 seek drop      \ seek to sector
+   block block-size read    \ read sector
+;
+
 : (.part-entry) ( part-entry )
    cr ." part-entry>active:        " dup part-entry>active c@ .d
    cr ." part-entry>start-head:    " dup part-entry>start-head c@ .d
@@ -204,7 +211,8 @@  CONSTANT /gpt-part-entry
          part-entry>sector-offset l@-le    ( current sector )
          dup to part-start to lpart-start  ( current )
          BEGIN
-            part-start read-sector          \ read EBR
+            part-start read-sector-ret          \ read EBR
+            block-size < IF UNLOOP 0 EXIT THEN
             1 partition>start-sector IF
                \ ." Logical Partition found at " part-start .d cr
                1+
@@ -279,6 +287,7 @@  CONSTANT /gpt-part-entry
    THEN
 
    count-dos-logical-partitions TO dos-logical-partitions
+   dos-logical-partitions 0= IF false EXIT THEN
 
    debug-disk-label? IF
       ." Found " dos-logical-partitions .d ." logical partitions" cr
@@ -352,6 +361,7 @@  CONSTANT /gpt-part-entry
    no-mbr? IF drop FALSE EXIT THEN  \ read MBR and check for DOS disk-label magic
 
    count-dos-logical-partitions TO dos-logical-partitions
+   dos-logical-partitions 0= IF 0 EXIT THEN
 
    debug-disk-label? IF
       ." Found " dos-logical-partitions .d ." logical partitions" cr