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Message-Id: <20230723074110.3705047-1-linma@zju.edu.cn>
Date: Sun, 23 Jul 2023 15:41:10 +0800
From: Lin Ma <linma@....edu.cn>
To: steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Lin Ma <linma@....edu.cn>
Subject: [PATCH v1] xfrm: add forgotten nla_policy for XFRMA_MTIMER_THRESH
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 <linma@....edu.cn>
---
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
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