| Message ID | 20210902190400.5257-1-paskripkin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | net: xfrm: fix shift-out-of-bounds in xfrm_get_default | expand |
On Thu, Sep 02, 2021 at 10:04:00PM +0300, Pavel Skripkin wrote: > Syzbot hit shift-out-of-bounds in xfrm_get_default. The problem was in > missing validation check for user data. > > up->dirmask comes from user-space, so we need to check if this value > is less than XFRM_USERPOLICY_DIRMASK_MAX to avoid shift-out-of-bounds bugs. > > Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy") > Reported-and-tested-by: syzbot+b2be9dd8ca6f6c73ee2d@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Applied, thanks Pavel!
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index b7b986520dc7..e4cf48c71315 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -2005,6 +2005,11 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh, return -EMSGSIZE; } + if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX) { + kfree_skb(r_skb); + return -EINVAL; + } + r_up = nlmsg_data(r_nlh); r_up->action = ((net->xfrm.policy_default & (1 << up->dirmask)) >> up->dirmask);
Syzbot hit shift-out-of-bounds in xfrm_get_default. The problem was in missing validation check for user data. up->dirmask comes from user-space, so we need to check if this value is less than XFRM_USERPOLICY_DIRMASK_MAX to avoid shift-out-of-bounds bugs. Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy") Reported-and-tested-by: syzbot+b2be9dd8ca6f6c73ee2d@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- net/xfrm/xfrm_user.c | 5 +++++ 1 file changed, 5 insertions(+)