4.9-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro viro@zeniv.linux.org.uk
commit 16a34adb9392b2fe4195267475ab5b472e55292c upstream.
We want it only for the stuff created by SB_KERNMOUNT mounts, *not* for their copies. As it is, creating a deep stack of bindings of /proc/*/ns/* somewhere in a new namespace and exiting yields a stack overflow.
Cc: stable@kernel.org Reported-by: Alexander Aring aring@mojatatu.com Bisected-by: Kirill Tkhai ktkhai@virtuozzo.com Tested-by: Kirill Tkhai ktkhai@virtuozzo.com Tested-by: Alexander Aring aring@mojatatu.com Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/namespace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/namespace.c +++ b/fs/namespace.c @@ -1033,7 +1033,8 @@ static struct mount *clone_mnt(struct mo goto out_free; }
- mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); + mnt->mnt.mnt_flags = old->mnt.mnt_flags; + mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); /* Don't allow unprivileged users to change mount flags */ if (flag & CL_UNPRIVILEGED) { mnt->mnt.mnt_flags |= MNT_LOCK_ATIME;