| From 9419a3191dcb27f24478d288abaab697228d28e6 Mon Sep 17 00:00:00 2001 |
| From: Al Viro <viro@zeniv.linux.org.uk> |
| Date: Thu, 4 Apr 2019 21:04:13 -0400 |
| Subject: acct_on(): don't mess with freeze protection |
| |
| From: Al Viro <viro@zeniv.linux.org.uk> |
| |
| commit 9419a3191dcb27f24478d288abaab697228d28e6 upstream. |
| |
| What happens there is that we are replacing file->path.mnt of |
| a file we'd just opened with a clone and we need the write |
| count contribution to be transferred from original mount to |
| new one. That's it. We do *NOT* want any kind of freeze |
| protection for the duration of switchover. |
| |
| IOW, we should just use __mnt_{want,drop}_write() for that |
| switchover; no need to bother with mnt_{want,drop}_write() |
| there. |
| |
| Tested-by: Amir Goldstein <amir73il@gmail.com> |
| Reported-by: syzbot+2a73a6ea9507b7112141@syzkaller.appspotmail.com |
| Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/internal.h | 2 -- |
| include/linux/mount.h | 2 ++ |
| kernel/acct.c | 4 ++-- |
| 3 files changed, 4 insertions(+), 4 deletions(-) |
| |
| --- a/fs/internal.h |
| +++ b/fs/internal.h |
| @@ -89,9 +89,7 @@ extern int sb_prepare_remount_readonly(s |
| |
| extern void __init mnt_init(void); |
| |
| -extern int __mnt_want_write(struct vfsmount *); |
| extern int __mnt_want_write_file(struct file *); |
| -extern void __mnt_drop_write(struct vfsmount *); |
| extern void __mnt_drop_write_file(struct file *); |
| |
| /* |
| --- a/include/linux/mount.h |
| +++ b/include/linux/mount.h |
| @@ -87,6 +87,8 @@ extern bool mnt_may_suid(struct vfsmount |
| |
| struct path; |
| extern struct vfsmount *clone_private_mount(const struct path *path); |
| +extern int __mnt_want_write(struct vfsmount *); |
| +extern void __mnt_drop_write(struct vfsmount *); |
| |
| struct file_system_type; |
| extern struct vfsmount *fc_mount(struct fs_context *fc); |
| --- a/kernel/acct.c |
| +++ b/kernel/acct.c |
| @@ -227,7 +227,7 @@ static int acct_on(struct filename *path |
| filp_close(file, NULL); |
| return PTR_ERR(internal); |
| } |
| - err = mnt_want_write(internal); |
| + err = __mnt_want_write(internal); |
| if (err) { |
| mntput(internal); |
| kfree(acct); |
| @@ -252,7 +252,7 @@ static int acct_on(struct filename *path |
| old = xchg(&ns->bacct, &acct->pin); |
| mutex_unlock(&acct->lock); |
| pin_kill(old); |
| - mnt_drop_write(mnt); |
| + __mnt_drop_write(mnt); |
| mntput(mnt); |
| return 0; |
| } |