btrfs: init csum_list before possible free

[mirror_ubuntu-bionic-kernel.git] / fs / open.c

diff --git a/fs/open.c b/fs/open.c
index 861efbefa6d78c4e39f229b90fbb8cdc11807ebf..d5362b96cd6be826d1f310cccbf16b03fc371802 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -383,6 +383,25 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
                                override_cred->cap_permitted;
        }
 
+       /*
+        * The new set of credentials can *only* be used in
+        * task-synchronous circumstances, and does not need
+        * RCU freeing, unless somebody then takes a separate
+        * reference to it.
+        *
+        * NOTE! This is _only_ true because this credential
+        * is used purely for override_creds() that installs
+        * it as the subjective cred. Other threads will be
+        * accessing ->real_cred, not the subjective cred.
+        *
+        * If somebody _does_ make a copy of this (using the
+        * 'get_current_cred()' function), that will clear the
+        * non_rcu field, because now that other user may be
+        * expecting RCU freeing. But normal thread-synchronous
+        * cred accesses will keep things non-RCY.
+        */
+       override_cred->non_rcu = 1;
+
        old_cred = override_creds(override_cred);
 retry:
        res = user_path_at(dfd, filename, lookup_flags, &path);
@@ -721,6 +740,12 @@ static int do_dentry_open(struct file *f,
                return 0;
        }
 
+       /* Any file opened for execve()/uselib() has to be a regular file. */
+       if (unlikely(f->f_flags & FMODE_EXEC && !S_ISREG(inode->i_mode))) {
+               error = -EACCES;
+               goto cleanup_file;
+       }
+
        if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
                error = get_write_access(inode);
                if (unlikely(error))
@@ -1212,3 +1237,21 @@ int nonseekable_open(struct inode *inode, struct file *filp)
 }
 
 EXPORT_SYMBOL(nonseekable_open);
+
+/*
+ * stream_open is used by subsystems that want stream-like file descriptors.
+ * Such file descriptors are not seekable and don't have notion of position
+ * (file.f_pos is always 0). Contrary to file descriptors of other regular
+ * files, .read() and .write() can run simultaneously.
+ *
+ * stream_open never fails and is marked to return int so that it could be
+ * directly used as file_operations.open .
+ */
+int stream_open(struct inode *inode, struct file *filp)
+{
+       filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
+       filp->f_mode |= FMODE_STREAM;
+       return 0;
+}
+
+EXPORT_SYMBOL(stream_open);