cifs: don't dereference smb_file_target before null check (8c6c9bed) · Commits · 戴 / test

There is a null check on dst_file->private data which suggests it can be potentially null. However, before this check, pointer smb_file_target is derived from dst_file->private and dereferenced in the call to tlink_tcon, hence there is a potential null pointer deference. Fix this by assigning smb_file_target and target_tcon after the null pointer sanity checks. Detected by CoverityScan, CID#1475302 ("Dereference before null check") Fixes: ("vfs: pull btrfs clone API to vfs layer") Signed-off-by:

Colin Ian King <colin.king@canonical.com> Signed-off-by:

Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -999,8 +999,8 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
		struct inode *src_inode = file_inode(src_file);
		struct inode *target_inode = file_inode(dst_file);
		struct cifsFileInfo *smb_file_src = src_file->private_data;
		struct cifsFileInfo *smb_file_target = dst_file->private_data;
		struct cifs_tcon *target_tcon = tlink_tcon(smb_file_target->tlink);
		struct cifsFileInfo *smb_file_target;
		struct cifs_tcon *target_tcon;
		unsigned int xid;
		int rc;

		@@ -1017,6 +1017,9 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
		goto out;
		}

		smb_file_target = dst_file->private_data;
		target_tcon = tlink_tcon(smb_file_target->tlink);

		/*
		* Note: cifs case is easier than btrfs since server responsible for
		* checks for proper open modes and file type and if it wants

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