| Message ID | 20210728163818.10744-1-paskripkin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [next] net: xfrm: fix shift-out-of-bounce | expand |
On Wed, Jul 28, 2021 at 07:38:18PM +0300, Pavel Skripkin wrote: > We need to check up->dirmask to avoid shift-out-of-bounce bug, > since up->dirmask comes from userspace. > > Also, added XFRM_USERPOLICY_DIRMASK_MAX constant to uapi to inform > user-space that up->dirmask has maximum possible value > > Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy") > Reported-and-tested-by: syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Applied, thanks a lot!
diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h index 6e8095106192..b96c1ea7166d 100644 --- a/include/uapi/linux/xfrm.h +++ b/include/uapi/linux/xfrm.h @@ -514,6 +514,7 @@ struct xfrm_user_offload { #define XFRM_OFFLOAD_INBOUND 2 struct xfrm_userpolicy_default { +#define XFRM_USERPOLICY_DIRMASK_MAX (sizeof(__u8) * 8) __u8 dirmask; __u8 action; }; diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index acc3a0dab331..03b66d154b2b 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1966,9 +1966,14 @@ static int xfrm_set_default(struct sk_buff *skb, struct nlmsghdr *nlh, { struct net *net = sock_net(skb->sk); struct xfrm_userpolicy_default *up = nlmsg_data(nlh); - u8 dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK; + u8 dirmask; u8 old_default = net->xfrm.policy_default; + if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX) + return -EINVAL; + + dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK; + net->xfrm.policy_default = (old_default & (0xff ^ dirmask)) | (up->action << up->dirmask);
We need to check up->dirmask to avoid shift-out-of-bounce bug, since up->dirmask comes from userspace. Also, added XFRM_USERPOLICY_DIRMASK_MAX constant to uapi to inform user-space that up->dirmask has maximum possible value Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy") Reported-and-tested-by: syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- include/uapi/linux/xfrm.h | 1 + net/xfrm/xfrm_user.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-)