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

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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
This commit is contained in:
Linus Torvalds 2016-06-10 12:10:02 -07:00
commit f5364c150a
3 changed files with 20 additions and 3 deletions
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13
fs/ecryptfs/kthread.c
View file

@ -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;
}

7
fs/proc/root.c
View file

@ -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);

3
kernel/sched/core.c
View file

@ -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())) {