From d38922949d377da7d47473c7868334408ae3b373 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 2 Nov 2010 16:22:50 -0400 Subject: [PATCH] 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 Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/file.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 71185d1d310a..777e7f42b5b1 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; -- 2.20.1