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proc: proc_pid_ns takes super_block as an argument

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syzbot found that

  touch /proc/testfile

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

Before c59f415a7c, 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: c59f415a7c ("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>
This commit is contained in:
Alexey Gladkov
2020-05-18 20:07:38 +02:00
committed by Eric W. Biederman
parent 2dd8083f6d
commit 9d78edeaec
9 changed files with 15 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/proc_fs.h
View File

@@ -202,9 +202,9 @@ int open_related_ns(struct ns_common *ns,
struct ns_common *(*get_ns)(struct ns_common *ns));
/* get the associated pid namespace for a file in procfs */
static inline struct pid_namespace *proc_pid_ns(const struct inode *inode)
static inline struct pid_namespace *proc_pid_ns(struct super_block *sb)
{
return proc_sb_info(inode->i_sb)->pid_ns;
return proc_sb_info(sb)->pid_ns;
}
#endif /* _LINUX_PROC_FS_H */