On Thu, 28 Oct 2010 05:44:34 +0200
Dan Carpenter <error27@xxxxxxxxx> wrote:
> On Wed, Oct 27, 2010 at 07:51:23PM -0400, Jeff Layton wrote:
> >
> > The above delta shouldn't be needed once the patches in Steve's tree
> > are pushed to Linus. I think what we should probably do is wait for
> > Steve to push to Linus and then do a patch to remove the first two
> > checks.
> >
> > Sound like a plan?
> >
>
> Sounds like a plan.
>
> regards,
> dan carpenter
>
Here's a respun patch that should fix these problems. I chickened out
on removing the check in find_writable_file.
It still seems like a bogus cargo-cult sort of thing. It should
probably be a BUG() if you call that function with a NULL pointer, but
I don't feel like tackling that just yet.
Dan, does this look ok to you? If so, I'll resend to Steve as an
"official" patch.
---------------------[snip]-----------------------
cifs: dereferencing first then checking (try #2)
This patch is based on Dan's original patch. His original description is
below:
Smatch complained about a couple checking for NULL after dereferencing
bugs. I'm not super familiar with the code so I did the conservative
thing and move the dereferences after the checks.
The dereferences in cifs_lock() and cifs_fsync() were added in
ba00ba64cf0 "cifs: make various routines use the cifsFileInfo->tcon
pointer". The dereference in find_writable_file() was added in
6508d904e6f "cifs: have find_readable/writable_file filter by fsuid".
The comments there say it's possible to trigger the NULL dereference
under stress.
Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/file.c | 10 +++-------
1 files changed, 3 insertions(+), 7 deletions(-)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index a566f15..a59b53f 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -755,12 +755,6 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
tcon = tlink_tcon(((struct cifsFileInfo *)file->private_data)->tlink);
-
- if (file->private_data == NULL) {
- rc = -EBADF;
- FreeXid(xid);
- return rc;
- }
netfid = ((struct cifsFileInfo *)file->private_data)->netfid;
if ((tcon->ses->capabilities & CAP_UNIX) &&
@@ -1155,7 +1149,7 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode,
bool fsuid_only)
{
struct cifsFileInfo *open_file;
- struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
+ struct cifs_sb_info *cifs_sb;
bool any_available = false;
int rc;
@@ -1169,6 +1163,8 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode,
return NULL;
}
+ cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
+
/* only filter by fsuid on multiuser mounts */
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
fsuid_only = false;
--
1.7.2.3
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