From 9d78edeaec759f997c303f286ecd39daee166f2a Mon Sep 17 00:00:00 2001 From: Alexey Gladkov Date: Mon, 18 May 2020 20:07:38 +0200 Subject: 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 Signed-off-by: Eric W. Biederman --- include/linux/proc_fs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/proc_fs.h') diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 2cb424e6f36a..6ec524d8842c 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -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 */ -- cgit v1.2.3