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Commit 1b0b9cc8 authored by Eric Biggers's avatar Eric Biggers Committed by Al Viro
Browse files

vfs: fsmount: add missing mntget() 



sys_fsmount() needs to take a reference to the new mount when adding it
to the anonymous mount namespace.  Otherwise the filesystem can be
unmounted while it's still in use, as found by syzkaller.

Reported-by: default avatarMark Rutland <mark.rutland@arm.com>
Reported-by: default avatar <syzbot+99de05d099a170867f22@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+7008b8b8ba7df475fdc8@syzkaller.appspotmail.com>
Fixes: 93766fbd ("vfs: syscall: Add fsmount() to create a mount for a superblock")
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 9e0babf2

fs/namespace.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -3445,6 +3445,7 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, 
	ns->root = mnt;

	ns->root = mnt;

	ns->mounts = 1;

	ns->mounts = 1;

	list_add(&mnt->mnt_list, &ns->list);

	list_add(&mnt->mnt_list, &ns->list);

	mntget(newmount.mnt);





	/* Attach to an apparent O_PATH fd with a note that we need to unmount

	/* Attach to an apparent O_PATH fd with a note that we need to unmount

	 * it, not just simply put it.

	 * it, not just simply put it.