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authorJeff Layton <jlayton@redhat.com>2010-11-02 16:22:50 -0400
committerSteve French <sfrench@us.ibm.com>2010-11-04 19:39:07 +0000
commitd38922949d377da7d47473c7868334408ae3b373 (patch)
tree322cf984f274c45da08d57acc74d29bb5c5e5048 /fs/cifs
parent6ef933a38ade555a175ecab9d803e6bb73399763 (diff)
cifs: dereferencing first then checking
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@gmail.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
Diffstat (limited to 'fs/cifs')
-rw-r--r--fs/cifs/file.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 71185d1d310..777e7f42b5b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -754,12 +754,6 @@ 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) &&
@@ -1154,7 +1148,7 @@ 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;
@@ -1168,6 +1162,8 @@ 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;