Commit 9d78edea authored by Alexey Gladkov's avatar Alexey Gladkov Committed by Eric W. Biederman
Browse files

proc: proc_pid_ns takes super_block as an argument 

syzbot found that

  touch /proc/testfile

causes NULL pointer dereference at tomoyo_get_local_path()
because inode of the dentry is NULL.

Before c59f415a, Tomoyo received pid_ns from proc's s_fs_info
directly. Since proc_pid_ns() can only work with inode, using it in
the tomoyo_get_local_path() was wrong.

To avoid creating more functions for getting proc_ns, change the
argument type of the proc_pid_ns() function. Then, Tomoyo can use
the existing super_block to get pid_ns.

Link: https://lkml.kernel.org/r/0000000000002f0c7505a5b0e04c@google.com
Link: https://lkml.kernel.org/r/20200518180738.2939611-1-gladkov.alexey@gmail.com


Reported-by: default avatar <syzbot+c1af344512918c61362c@syzkaller.appspotmail.com>
Fixes: c59f415a ("Use proc_pid_ns() to get pid_namespace from the proc superblock")
Signed-off-by: default avatarAlexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 2dd8083f

fs/locks.c

+2 −2
Original line number Diff line number Diff line
@@ -2823,7 +2823,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, 
{

	struct inode *inode = NULL;

	unsigned int fl_pid;

	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file));

	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);



	fl_pid = locks_translate_pid(fl, proc_pidns);

	/*
@@ -2901,7 +2901,7 @@ static int locks_show(struct seq_file *f, void *v) 
{

	struct locks_iterator *iter = f->private;

	struct file_lock *fl, *bfl;

	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file));

	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);



	fl = hlist_entry(v, struct file_lock, fl_link);

fs/proc/array.c

+1 −1
Original line number Diff line number Diff line
@@ -728,7 +728,7 @@ static int children_seq_show(struct seq_file *seq, void *v) 
{

	struct inode *inode = file_inode(seq->file);



	seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode)));

	seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode->i_sb)));

	return 0;

}

fs/proc/base.c

+5 −5
Original line number Diff line number Diff line
@@ -754,7 +754,7 @@ static const struct inode_operations proc_def_inode_operations = { 
static int proc_single_show(struct seq_file *m, void *v)

{

	struct inode *inode = m->private;

	struct pid_namespace *ns = proc_pid_ns(inode);

	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);

	struct pid *pid = proc_pid(inode);

	struct task_struct *task;

	int ret;
@@ -1423,7 +1423,7 @@ static const struct file_operations proc_fail_nth_operations = { 
static int sched_show(struct seq_file *m, void *v)

{

	struct inode *inode = m->private;

	struct pid_namespace *ns = proc_pid_ns(inode);

	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);

	struct task_struct *p;



	p = get_proc_task(inode);
@@ -2466,7 +2466,7 @@ static int proc_timers_open(struct inode *inode, struct file *file) 
		return -ENOMEM;



	tp->pid = proc_pid(inode);

	tp->ns = proc_pid_ns(inode);

	tp->ns = proc_pid_ns(inode->i_sb);

	return 0;

}
@@ -3377,7 +3377,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx) 
{

	struct tgid_iter iter;

	struct proc_fs_info *fs_info = proc_sb_info(file_inode(file)->i_sb);

	struct pid_namespace *ns = proc_pid_ns(file_inode(file));

	struct pid_namespace *ns = proc_pid_ns(file_inode(file)->i_sb);

	loff_t pos = ctx->pos;



	if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
@@ -3730,7 +3730,7 @@ static int proc_task_readdir(struct file *file, struct dir_context *ctx) 
	/* f_version caches the tgid value that the last readdir call couldn't

	 * return. lseek aka telldir automagically resets f_version to 0.

	 */

	ns = proc_pid_ns(inode);

	ns = proc_pid_ns(inode->i_sb);

	tid = (int)file->f_version;

	file->f_version = 0;

	for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);

fs/proc/self.c

+1 −1
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ static const char *proc_self_get_link(struct dentry *dentry, 
				      struct inode *inode,

				      struct delayed_call *done)

{

	struct pid_namespace *ns = proc_pid_ns(inode);

	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);

	pid_t tgid = task_tgid_nr_ns(current, ns);

	char *name;

fs/proc/thread_self.c

+1 −1
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ static const char *proc_thread_self_get_link(struct dentry *dentry, 
					     struct inode *inode,

					     struct delayed_call *done)

{

	struct pid_namespace *ns = proc_pid_ns(inode);

	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);

	pid_t tgid = task_tgid_nr_ns(current, ns);

	pid_t pid = task_pid_nr_ns(current, ns);

	char *name;

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