The previous commit 4e484b3e969b ("xfrm: rate limit SA mapping change
message to user space") added one additional attribute named
XFRMA_MTIMER_THRESH and described its type at compat_policy
(net/xfrm/xfrm_compat.c).
However, the author forgot to also describe the nla_policy at
xfrma_policy (net/xfrm/xfrm_user.c). Hence, this suppose NLA_U32 (4
bytes) value can be faked as empty (0 bytes) by a malicious user, which
leads to 4 bytes overflow read and heap information leak when parsing
nlattrs.
To exploit this, one malicious user can spray the SLUB objects and then
leverage this 4 bytes OOB read to leak the heap data into
x->mapping_maxage (see xfrm_update_ae_params(...)), and leak it to
userspace via copy_to_user_state_extra(...).
The above bug is assigned CVE-2023-3773. To fix it, this commit just
completes the nla_policy description for XFRMA_MTIMER_THRESH, which
enforces the length check and avoids such OOB read.
Fixes: 4e484b3e969b ("xfrm: rate limit SA mapping change message to user space")
Signed-off-by: Lin Ma <[email protected]>
---
net/xfrm/xfrm_user.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index c34a2a06ca94..ab0e73c1e352 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -3035,6 +3035,7 @@ const struct nla_policy xfrma_policy[XFRMA_MAX+1] = {
[XFRMA_SET_MARK] = { .type = NLA_U32 },
[XFRMA_SET_MARK_MASK] = { .type = NLA_U32 },
[XFRMA_IF_ID] = { .type = NLA_U32 },
+ [XFRMA_MTIMER_THRESH] = { .type = NLA_U32 },
};
EXPORT_SYMBOL_GPL(xfrma_policy);
--
2.17.1
On Sun, Jul 23, 2023 at 03:41:10PM +0800, Lin Ma wrote:
> The previous commit 4e484b3e969b ("xfrm: rate limit SA mapping change
> message to user space") added one additional attribute named
> XFRMA_MTIMER_THRESH and described its type at compat_policy
> (net/xfrm/xfrm_compat.c).
>
> However, the author forgot to also describe the nla_policy at
> xfrma_policy (net/xfrm/xfrm_user.c). Hence, this suppose NLA_U32 (4
> bytes) value can be faked as empty (0 bytes) by a malicious user, which
> leads to 4 bytes overflow read and heap information leak when parsing
> nlattrs.
>
> To exploit this, one malicious user can spray the SLUB objects and then
> leverage this 4 bytes OOB read to leak the heap data into
> x->mapping_maxage (see xfrm_update_ae_params(...)), and leak it to
> userspace via copy_to_user_state_extra(...).
>
> The above bug is assigned CVE-2023-3773. To fix it, this commit just
> completes the nla_policy description for XFRMA_MTIMER_THRESH, which
> enforces the length check and avoids such OOB read.
>
> Fixes: 4e484b3e969b ("xfrm: rate limit SA mapping change message to user space")
> Signed-off-by: Lin Ma <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
On Sun, Jul 23, 2023 at 03:41:10PM +0800, Lin Ma wrote:
> The previous commit 4e484b3e969b ("xfrm: rate limit SA mapping change
> message to user space") added one additional attribute named
> XFRMA_MTIMER_THRESH and described its type at compat_policy
> (net/xfrm/xfrm_compat.c).
>
> However, the author forgot to also describe the nla_policy at
> xfrma_policy (net/xfrm/xfrm_user.c). Hence, this suppose NLA_U32 (4
> bytes) value can be faked as empty (0 bytes) by a malicious user, which
> leads to 4 bytes overflow read and heap information leak when parsing
> nlattrs.
>
> To exploit this, one malicious user can spray the SLUB objects and then
> leverage this 4 bytes OOB read to leak the heap data into
> x->mapping_maxage (see xfrm_update_ae_params(...)), and leak it to
> userspace via copy_to_user_state_extra(...).
>
> The above bug is assigned CVE-2023-3773.
This CVE is a joke, you need to be root to execute this attack.
Anyway change is ok.
Reviewed-by: Leon Romanovsky <[email protected]>
Hello Leon,
>
> This CVE is a joke, you need to be root to execute this attack.
>
Not really, this call routine only checks
if (!netlink_net_capable(skb, CAP_NET_ADMIN))
return -EPERM;
and any users in most vendor kernel can create a network namespace to
get such privilege and trigger this bug.
> Anyway change is ok.
> Reviewed-by: Leon Romanovsky <[email protected]>
Regards
Lin
On Wed, Jul 26, 2023 at 09:32:43PM +0800, Lin Ma wrote:
> Hello Leon,
>
> >
> > This CVE is a joke, you need to be root to execute this attack.
> >
>
> Not really, this call routine only checks
>
> if (!netlink_net_capable(skb, CAP_NET_ADMIN))
> return -EPERM;
>
> and any users in most vendor kernel can create a network namespace to
> get such privilege and trigger this bug.
ok, fair enough.
>
> > Anyway change is ok.
> > Reviewed-by: Leon Romanovsky <[email protected]>
>
> Regards
> Lin
On Sun, Jul 23, 2023 at 03:41:10PM +0800, Lin Ma wrote:
> The previous commit 4e484b3e969b ("xfrm: rate limit SA mapping change
> message to user space") added one additional attribute named
> XFRMA_MTIMER_THRESH and described its type at compat_policy
> (net/xfrm/xfrm_compat.c).
>
> However, the author forgot to also describe the nla_policy at
> xfrma_policy (net/xfrm/xfrm_user.c). Hence, this suppose NLA_U32 (4
> bytes) value can be faked as empty (0 bytes) by a malicious user, which
> leads to 4 bytes overflow read and heap information leak when parsing
> nlattrs.
>
> To exploit this, one malicious user can spray the SLUB objects and then
> leverage this 4 bytes OOB read to leak the heap data into
> x->mapping_maxage (see xfrm_update_ae_params(...)), and leak it to
> userspace via copy_to_user_state_extra(...).
>
> The above bug is assigned CVE-2023-3773. To fix it, this commit just
> completes the nla_policy description for XFRMA_MTIMER_THRESH, which
> enforces the length check and avoids such OOB read.
>
> Fixes: 4e484b3e969b ("xfrm: rate limit SA mapping change message to user space")
> Signed-off-by: Lin Ma <[email protected]>
Also applied, thanks Lin!