[PATCH 4.14 06/77] af_key: Fix send_acquire race with pfkey_register

Greg Kroah-Hartman
2022-12-05T19:14:45Z

From: Herbert Xu <herbert@gondor.apana.org.au>

[ Upstream commit 7f57f8165cb6d2c206e2b9ada53b9e2d6d8af42f ]

The function pfkey_send_acquire may race with pfkey_register
(which could even be in a different name space). This may result
in a buffer overrun.

Allocating the maximum amount of memory that could be used prevents
this.

Reported-by: syzbot+1e9af9185d8850e2c2fa@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/key/af_key.c | 32 ++++++++++++++++++++++----------
1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 5f0d6a567a1e..09a0ea651f57 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2913,7 +2913,7 @@ static int count_ah_combs(const struct xfrm_tmpl *t)
break;
if (!aalg->pfkey_supported)
continue;
- if (aalg_tmpl_set(t, aalg) && aalg->available)
+ if (aalg_tmpl_set(t, aalg))
sz += sizeof(struct sadb_comb);
}
return sz + sizeof(struct sadb_prop);
@@ -2931,7 +2931,7 @@ static int count_esp_combs(const struct xfrm_tmpl *t)
if (!ealg->pfkey_supported)
continue;

- if (!(ealg_tmpl_set(t, ealg) && ealg->available))
+ if (!(ealg_tmpl_set(t, ealg)))
continue;

for (k = 1; ; k++) {
@@ -2942,16 +2942,17 @@ static int count_esp_combs(const struct xfrm_tmpl *t)
if (!aalg->pfkey_supported)
continue;

- if (aalg_tmpl_set(t, aalg) && aalg->available)
+ if (aalg_tmpl_set(t, aalg))
sz += sizeof(struct sadb_comb);
}
}
return sz + sizeof(struct sadb_prop);
}

-static void dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
+static int dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
{
struct sadb_prop *p;
+ int sz = 0;
int i;

p = skb_put(skb, sizeof(struct sadb_prop));
@@ -2979,13 +2980,17 @@ static void dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
c->sadb_comb_soft_addtime = 20*60*60;
c->sadb_comb_hard_usetime = 8*60*60;
c->sadb_comb_soft_usetime = 7*60*60;
+ sz += sizeof(*c);
}
}
+
+ return sz + sizeof(*p);
}

-static void dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
+static int dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
{
struct sadb_prop *p;
+ int sz = 0;
int i, k;

p = skb_put(skb, sizeof(struct sadb_prop));
@@ -3027,8 +3032,11 @@ static void dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
c->sadb_comb_soft_addtime = 20*60*60;
c->sadb_comb_hard_usetime = 8*60*60;
c->sadb_comb_soft_usetime = 7*60*60;
+ sz += sizeof(*c);
}
}
+
+ return sz + sizeof(*p);
}

static int key_notify_policy_expire(struct xfrm_policy *xp, const struct km_event *c)
@@ -3158,6 +3166,7 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
struct sadb_x_sec_ctx *sec_ctx;
struct xfrm_sec_ctx *xfrm_ctx;
int ctx_size = 0;
+ int alg_size = 0;

sockaddr_size = pfkey_sockaddr_size(x->props.family);
if (!sockaddr_size)
@@ -3169,16 +3178,16 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
sizeof(struct sadb_x_policy);

if (x->id.proto == IPPROTO_AH)
- size += count_ah_combs(t);
+ alg_size = count_ah_combs(t);
else if (x->id.proto == IPPROTO_ESP)
- size += count_esp_combs(t);
+ alg_size = count_esp_combs(t);

if ((xfrm_ctx = x->security)) {
ctx_size = PFKEY_ALIGN8(xfrm_ctx->ctx_len);
size += sizeof(struct sadb_x_sec_ctx) + ctx_size;
}

- skb = alloc_skb(size + 16, GFP_ATOMIC);
+ skb = alloc_skb(size + alg_size + 16, GFP_ATOMIC);
if (skb == NULL)
return -ENOMEM;

@@ -3232,10 +3241,13 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
pol->sadb_x_policy_priority = xp->priority;

/* Set sadb_comb's. */
+ alg_size = 0;
if (x->id.proto == IPPROTO_AH)
- dump_ah_combs(skb, t);
+ alg_size = dump_ah_combs(skb, t);
else if (x->id.proto == IPPROTO_ESP)
- dump_esp_combs(skb, t);
+ alg_size = dump_esp_combs(skb, t);
+
+ hdr->sadb_msg_len += alg_size / 8;

/* security context */
if (xfrm_ctx) {
--
2.35.1