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 --- security/tomoyo/realpath.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c index 08b096e2f7e3..df4798980416 100644 --- a/security/tomoyo/realpath.c +++ b/security/tomoyo/realpath.c @@ -162,7 +162,7 @@ static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer, if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') { char *ep; const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10); - struct pid_namespace *proc_pidns = proc_pid_ns(d_inode(dentry)); + struct pid_namespace *proc_pidns = proc_pid_ns(sb); if (*ep == '/' && pid && pid == task_tgid_nr_ns(current, proc_pidns)) { -- cgit v1.2.3-58-ga151