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 c59f415a7cb6, 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: syzbot+c1af344512918c61362c@syzkaller.appspotmail.com
Fixes: c59f415a7cb6 ("Use proc_pid_ns() to get pid_namespace from the proc superblock")
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/fs/locks.c b/fs/locks.c
index 399c5db..ab702d6 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -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);