Re: kern/43375: panic when mount(8)ing umass(4) device (Sony DSC-H50 Digital Camera)

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR kern/43375; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/43375: panic when mount(8)ing umass(4) device (Sony
        DSC-H50 Digital Camera)
Date: Mon, 31 May 2010 02:19:05 +0000

 On Mon, May 31, 2010 at 02:10:05AM +0000, David Holland wrote:
  >  It may also be helpful to add this:
  >  
  >     if (size == 0) {
  >             panic("bread: zero-length buf requested\n");
  >     }
  >  
  >  to the top of bread() (at around line 732 of sys/kern/vfs_bio.c),
  >  because if that goes off it will save the trouble of wading through
  >  the buffer code.
 
 also try this patch:
 
 Index: fs/msdosfs/msdosfs_vfsops.c
 ===================================================================
 RCS file: /cvsroot/src/sys/fs/msdosfs/msdosfs_vfsops.c,v
 retrieving revision 1.85
 diff -u -p -r1.85 msdosfs_vfsops.c
 --- sys/fs/msdosfs/msdosfs_vfsops.c    13 Apr 2010 10:12:43 -0000      1.85
 +++ sys/fs/msdosfs/msdosfs_vfsops.c    31 May 2010 02:15:45 -0000
 @@ -498,6 +498,10 @@ msdosfs_mountfs(struct vnode *devvp, str
                psize = 0;
                error = 0;
        }
 +      if (secsize == 0) {
 +              printf("msdosfs: getdisksize said the sector size was 0\n");
 +              secsize = DEV_BSIZE;
 +      }
  
        if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
                bsize = secsize;
 
 
 I don't know if this is where the zero-length read is coming from, but
 it's not a bad bet.
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost