[SRU][J:linux-bluefield][PATCH v2 5/6] xfrm: add forgotten nla_policy for XFRMA_MTIMER_THRESH

[Tony Duan]

From: Lin Ma <linma at zju.edu.cn>

BugLink: https://bugs.launchpad.net/bugs/2044427

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 at zju.edu.cn>
Reviewed-by: Simon Horman <simon.horman at corigine.com>
Reviewed-by: Leon Romanovsky <leonro at nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert at secunet.com>
(cherry picked from commit 5e2424708da7207087934c5c75211e8584d553a0)
Signed-off-by: Tony Duan <yifeid at nvidia.com>
---
 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 2b9f760..5e2988b 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2884,6 +2884,7 @@ static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
 	[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);
 
-- 
1.8.3.1