Merge branch 'stacking-fixes' (vfs stacking fixes from Jann)

Merge filesystem stacking fixes from Jann Horn.

* emailed patches from Jann Horn <jannh@google.com>:
  sched: panic on corrupted stack end
  ecryptfs: forbid opening files without mmap handler
  proc: prevent stacking filesystems on top

diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index 866bb18..e818f5a 100644 (file)
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c
@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/wait.h>
 #include <linux/mount.h>
+#include <linux/file.h>
 #include "ecryptfs_kernel.h"
 
 struct ecryptfs_open_req {
@@ -147,7 +148,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
        flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR;
        (*lower_file) = dentry_open(&req.path, flags, cred);
        if (!IS_ERR(*lower_file))
-               goto out;
+               goto have_file;
        if ((flags & O_ACCMODE) == O_RDONLY) {
                rc = PTR_ERR((*lower_file));
                goto out;
@@ -165,8 +166,16 @@ int ecryptfs_privileged_open(struct file **lower_file,
        mutex_unlock(&ecryptfs_kthread_ctl.mux);
        wake_up(&ecryptfs_kthread_ctl.wait);
        wait_for_completion(&req.done);
-       if (IS_ERR(*lower_file))
+       if (IS_ERR(*lower_file)) {
                rc = PTR_ERR(*lower_file);
+               goto out;
+       }
+have_file:
+       if ((*lower_file)->f_op->mmap == NULL) {
+               fput(*lower_file);
+               *lower_file = NULL;
+               rc = -EMEDIUMTYPE;
+       }
 out:
        return rc;
 }

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 55bc7d6..0670278 100644 (file)
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -121,6 +121,13 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
        if (IS_ERR(sb))
                return ERR_CAST(sb);
 
+       /*
+        * procfs isn't actually a stacking filesystem; however, there is
+        * too much magic going on inside it to permit stacking things on
+        * top of it
+        */
+       sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
+
        if (!proc_parse_options(options, ns)) {
                deactivate_locked_super(sb);
                return ERR_PTR(-EINVAL);

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 385c947..017d539 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3170,7 +3170,8 @@ static noinline void __schedule_bug(struct task_struct *prev)
 static inline void schedule_debug(struct task_struct *prev)
 {
 #ifdef CONFIG_SCHED_STACK_END_CHECK
-       BUG_ON(task_stack_end_corrupted(prev));
+       if (task_stack_end_corrupted(prev))
+               panic("corrupted stack end detected inside scheduler\n");
 #endif
 
        if (unlikely(in_atomic_preempt_off())) {