[PATCH] fdisk: fix segfault on bsd label

[PATCH] fdisk: fix segfault on bsd label

[Davidlohr Bueso]

From: Davidlohr Bueso <dave@gnu.org>

Commit 8db8295d824cd0c8cba9385e4635d6e311d69d3f added a regression that causes the program to crash when
touching the partition structure (pte) for BSD/OSF labels. Since DOS has its own initialization function,
allow BSD labels to use it as well.

Steps to reproduce:

$> fdisk bsd.img (obtained from blkid regression test files)
Command (m for help): p
...
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Segmentation fault

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
---
As discussed, this is a temporary fix, a nicer way of initializing bsd structures will be implemented in the short future. 

 fdisk/fdisk.c         |    2 ++
 fdisk/fdiskdoslabel.c |    2 +-
 fdisk/fdiskdoslabel.h |    1 +
 3 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
index acc84d1..dccaf27 100644
--- a/fdisk/fdisk.c
+++ b/fdisk/fdisk.c
@@ -763,6 +763,8 @@ static int get_boot(int try_only) {
 			return 0;
 
 	if (check_osf_label()) {
+		/* intialize partitions for BSD as well */
+		dos_init();
 		if (!valid_part_table_flag(MBRbuffer)) {
 			disklabel = OSF_LABEL;
 			return 0;
diff --git a/fdisk/fdiskdoslabel.c b/fdisk/fdiskdoslabel.c
index 6a9a044..b91702a 100644
--- a/fdisk/fdiskdoslabel.c
+++ b/fdisk/fdiskdoslabel.c
@@ -54,7 +54,7 @@ static void clear_partition(struct partition *p)
 	set_nr_sects(p,0);
 }
 
-static void dos_init(void)
+void dos_init(void)
 {
 	int i;
 
diff --git a/fdisk/fdiskdoslabel.h b/fdisk/fdiskdoslabel.h
index f5568df..1897b6c 100644
--- a/fdisk/fdiskdoslabel.h
+++ b/fdisk/fdiskdoslabel.h
@@ -48,5 +48,6 @@ extern void dos_set_mbr_id(void);
 extern void dos_delete_partition(int i);
 extern int check_dos_label(void);
 extern int is_dos_partition(int t);
+extern void dos_init(void);
 
 #endif
-- 
1.7.8.3

Re: [PATCH] fdisk: fix segfault on bsd label

[Francesco Cosoleto]

2012/5/4 Davidlohr Bueso <dave@gnu.org>:
> From: Davidlohr Bueso <dave@gnu.org>
>
> Commit 8db8295d824cd0c8cba9385e4635d6e311d69d3f added a regression that causes the program to crash when
> touching the partition structure (pte) for BSD/OSF labels. Since DOS has its own initialization function,
> allow BSD labels to use it as well.
>
> Steps to reproduce:
>
> $> fdisk bsd.img (obtained from blkid regression test files)
> Command (m for help): p
> ...
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00000000
>
> Segmentation fault

Thanks Davidlohr for pointing out that regression. Does it occurs with
the command to print the partition table when the drive has a BSD
label and hasn't a valid DOS label, and it has no partition? Fdisk
switches from BSD label to DOS label without initializing DOS
structures, right?

fdisk.c:
    bsd_command_prompt();
    /* If we return we may want to make an empty DOS label? */
    disklabel = DOS_LABEL;

Re: [PATCH] fdisk: fix segfault on bsd label

[Davidlohr Bueso]

On Fri, 2012-05-04 at 15:53 +0200, Francesco Cosoleto wrote:
> 2012/5/4 Davidlohr Bueso <dave@gnu.org>:
> > From: Davidlohr Bueso <dave@gnu.org>
> >
> > Commit 8db8295d824cd0c8cba9385e4635d6e311d69d3f added a regression that causes the program to crash when
> > touching the partition structure (pte) for BSD/OSF labels. Since DOS has its own initialization function,
> > allow BSD labels to use it as well.
> >
> > Steps to reproduce:
> >
> > $> fdisk bsd.img (obtained from blkid regression test files)
> > Command (m for help): p
> > ...
> > I/O size (minimum/optimal): 512 bytes / 512 bytes
> > Disk identifier: 0x00000000
> >
> > Segmentation fault
> 
> Thanks Davidlohr for pointing out that regression. Does it occurs with
> the command to print the partition table when the drive has a BSD
> label and hasn't a valid DOS label, and it has no partition? Fdisk
> switches from BSD label to DOS label without initializing DOS
> structures, right?

>From my analysis, yes.

> 
> fdisk.c:
>     bsd_command_prompt();
>     /* If we return we may want to make an empty DOS label? */
>     disklabel = DOS_LABEL;
> 

Re: [PATCH] fdisk: fix segfault on bsd label

[Karel Zak]

On Fri, May 04, 2012 at 07:08:30PM +0200, Davidlohr Bueso wrote:
> On Fri, 2012-05-04 at 15:53 +0200, Francesco Cosoleto wrote:
> > 2012/5/4 Davidlohr Bueso <dave@gnu.org>:
> > > From: Davidlohr Bueso <dave@gnu.org>
> > >
> > > Commit 8db8295d824cd0c8cba9385e4635d6e311d69d3f added a regression that causes the program to crash when
> > > touching the partition structure (pte) for BSD/OSF labels. Since DOS has its own initialization function,
> > > allow BSD labels to use it as well.
> > >
> > > Steps to reproduce:
> > >
> > > $> fdisk bsd.img (obtained from blkid regression test files)
> > > Command (m for help): p
> > > ...
> > > I/O size (minimum/optimal): 512 bytes / 512 bytes
> > > Disk identifier: 0x00000000
> > >
> > > Segmentation fault
> > 
> > Thanks Davidlohr for pointing out that regression. Does it occurs with
> > the command to print the partition table when the drive has a BSD
> > label and hasn't a valid DOS label, and it has no partition? Fdisk
> > switches from BSD label to DOS label without initializing DOS
> > structures, right?
> 
> From my analysis, yes.

 Just note that some labels are nested -- for example BSD, minix
 unixware, ... are subtypes (nested partition tables) within DOS.

 This parent->child relationship will be also necessary to support
 in new fdisk API.

    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH] fdisk: fix segfault on bsd label

[Karel Zak]

On Fri, May 04, 2012 at 01:35:32PM +0200, Davidlohr Bueso wrote:
>  fdisk/fdisk.c         |    2 ++
>  fdisk/fdiskdoslabel.c |    2 +-
>  fdisk/fdiskdoslabel.h |    1 +
>  3 files changed, 4 insertions(+), 1 deletions(-)

 Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com