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* [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default
@ 2021-09-02 19:04 Pavel Skripkin
2021-09-10 9:50 ` Steffen Klassert
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Skripkin @ 2021-09-02 19:04 UTC (permalink / raw)
To: steffen.klassert, herbert, davem, kuba
Cc: netdev, linux-kernel, Pavel Skripkin, syzbot+b2be9dd8ca6f6c73ee2d
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(+)
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);
--
2.33.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default
2021-09-02 19:04 [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default Pavel Skripkin
@ 2021-09-10 9:50 ` Steffen Klassert
0 siblings, 0 replies; 2+ messages in thread
From: Steffen Klassert @ 2021-09-10 9:50 UTC (permalink / raw)
To: Pavel Skripkin
Cc: herbert, davem, kuba, netdev, linux-kernel, syzbot+b2be9dd8ca6f6c73ee2d
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!
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-09-02 19:04 [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default Pavel Skripkin
2021-09-10 9:50 ` Steffen Klassert
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