I acknowledge this bug in the function unionfs_setattr(). It will bring up kernel oops.
Best Regards Zhaohui Wang > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:unionfs- > [EMAIL PROTECTED] On Behalf Of Erez Zadok > Sent: Sunday, August 03, 2008 1:52 PM > To: Tetsuo Handa > Cc: [EMAIL PROTECTED] > Subject: Re: [Unionfs] NULL pointer dereference if copyup_dentry() > failed? > > In message <[EMAIL PROTECTED]>, > Tetsuo Handa writes: > > Hello. > > > > I noticed that the below sequence triggers NULL pointer dereference > > if copyup_dentry() failed by some reason (e.g. mandatory access > control). > > / (which contains /tmp/ ) partition is an ext3 filesystem. > > > > [EMAIL PROTECTED] ~]# ls -l /tmp/1/ /tmp/2/ > > /tmp/1/: > > total 0 > > > > /tmp/2/: > > total 0 > > [EMAIL PROTECTED] ~]# touch /tmp/2/foo > > [EMAIL PROTECTED] ~]# mount -t unionfs -o dirs=/tmp/1=rw:/tmp/2=ro none > /mnt/ > > [EMAIL PROTECTED] ~]# touch /mnt/foo > > > > The below dmesg is obtained by "touch /mnt/foo" > > with permission to open() /mnt/foo for writing > > and without permission to call chmod()/chown(), > > using unionfs-2.3.3_for_2.6.24.5 with the printk() patch applied. > [...] > > EIP: [<e08780ec>] unionfs_setattr+0x324/0x35b [unionfs] SS:ESP > 0068:defbce5c > [...] > > Dear Tetsuo, > > Was this a vanilla 2.6.24.5 kernel, or did it have other patches > applied? > In particular, are you using any "special" MAC system or the like, ala > selinux, smack, etc.? I'd like to be able to reproduce this on my end. > > Since you were able to stick printk's in unionfs_setattr, can you add a > few > more closer to the end (0x324/0x35b) and try to narrow down where's the > null > deref? > > In the steps above: it looks fairly simple (ie. no funky chroot, bind > mounts, pivot_root, etc.) right? > > Do you know what's the condition which caused copyup_dentry (in > unionfs_setattr) to fail? Can you print the errno? > > If you don't mind, please open a bugzilla report at > https://bugzilla.filesystems.org/, give me pointers to any patches you > applied to the kernel, kernel .config used, etc. > > BTW, does the problem still exist in unionfs-2.4? > > Thanks, > Erez. > _______________________________________________ > unionfs mailing list: http://unionfs.filesystems.org/ > unionfs@mail.fsl.cs.sunysb.edu > http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs _______________________________________________ unionfs mailing list: http://unionfs.filesystems.org/ unionfs@mail.fsl.cs.sunysb.edu http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
