Commit 171d449a authored Feb 09, 2020 by Xin Long Committed by Steffen Klassert Feb 12, 2020

xfrm: fix uctx len check in verify_sec_ctx_len



It's not sufficient to do 'uctx->len != (sizeof(struct xfrm_user_sec_ctx) +
uctx->ctx_len)' check only, as uctx->len may be greater than nla_len(rt),
in which case it will cause slab-out-of-bounds when accessing uctx->ctx_str
later.

This patch is to fix it by return -EINVAL when uctx->len > nla_len(rt).

Fixes: df71837d ("[LSM-IPSec]: Security association restriction.")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

parent f1ed1026

net/xfrm/xfrm_user.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -110,7 +110,8 @@ static inline int verify_sec_ctx_len(struct nlattr **attrs)
		return 0;

		uctx = nla_data(rt);
		if (uctx->len != (sizeof(struct xfrm_user_sec_ctx) + uctx->ctx_len))
		if (uctx->len > nla_len(rt) \|\|
		uctx->len != (sizeof(struct xfrm_user_sec_ctx) + uctx->ctx_len))
		return -EINVAL;

		return 0;

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