Re: fs/xfs/xfs_vnodeops.c:xfs_readdir(): NULL variable dereferenced

Adrian Bunk
2006-07-08T19:46:10Z

On Fri, Jul 07, 2006 at 09:32:46AM +1000, David Chinner wrote:
> On Thu, Jul 06, 2006 at 11:13:20PM +0200, Adrian Bunk wrote:
> > The Coverity checker spotted the following:
> >
> > <-- snip -->
> >
> > ...
> > STATIC int
> > xfs_readdir(
> > bhv_desc_t *dir_bdp,
> > uio_t *uiop,
> > cred_t *credp,
> > int *eofp)
> > {
> > xfs_inode_t *dp;
> > xfs_trans_t *tp = NULL;
> > int error = 0;
> > uint lock_mode;
> >
> > vn_trace_entry(BHV_TO_VNODE(dir_bdp), __FUNCTION__,
> > (inst_t *)__return_address);
> > dp = XFS_BHVTOI(dir_bdp);
> >
> > if (XFS_FORCED_SHUTDOWN(dp->i_mount))
> > return XFS_ERROR(EIO);
> >
> > lock_mode = xfs_ilock_map_shared(dp);
> > error = xfs_dir_getdents(tp, dp, uiop, eofp);
> > xfs_iunlock_map_shared(dp, lock_mode);
> > return error;
> > }
> > ...
> >
> > <-- snip -->
> >
> > Note that tp is never assigned any value other than NULL (and the
> > Coverity checker found a way how tp might be dereferenced four function
> > calls later).
>
> Then the bug is probably in the function call that uses tp without
> first checking whether it's null. Can you tell us where that dereference
> occurs?

xfs_readdir()
xfs_dir_getdents()
xfs_dir2_leaf_getdents()
xfs_bmapi()
xfs_trans_log_inode()
tp->t_flags |= XFS_TRANS_DIRTY;

> Cheers,
>
> Dave.

cu
Adrian

--

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of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
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