diff options
Diffstat (limited to 'CVE-2020-16119-DCCP-CCID-structure-use-after-free.patch')
| -rw-r--r-- | CVE-2020-16119-DCCP-CCID-structure-use-after-free.patch | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/CVE-2020-16119-DCCP-CCID-structure-use-after-free.patch b/CVE-2020-16119-DCCP-CCID-structure-use-after-free.patch new file mode 100644 index 000000000..7eb981e45 --- /dev/null +++ b/CVE-2020-16119-DCCP-CCID-structure-use-after-free.patch @@ -0,0 +1,305 @@ +From MAILER-DAEMON Wed Oct 14 16:34:37 2020 +From: Kleber Sacilotto de Souza <kleber.souza@canonical.com> +To: netdev@vger.kernel.org +Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>, "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Thadeu Lima de Souza Cascardo <cascardo@canonical.com>, "Gustavo A. R. Silva" <gustavoars@kernel.org>, "Alexander A. Klimov" <grandmaster@al2klimov.de>, Kees Cook <keescook@chromium.org>, Eric Dumazet <edumazet@google.com>, Alexey Kodanev <alexey.kodanev@oracle.com>, dccp@vger.kernel.org, linux-kernel@vger.kernel.org +Subject: [PATCH 1/2] dccp: ccid: move timers to struct dccp_sock +Date: Tue, 13 Oct 2020 19:18:48 +0200 +Message-Id: <20201013171849.236025-2-kleber.souza@canonical.com> +In-Reply-To: <20201013171849.236025-1-kleber.souza@canonical.com> +References: <20201013171849.236025-1-kleber.souza@canonical.com> +List-ID: <linux-kernel.vger.kernel.org> +X-Mailing-List: linux-kernel@vger.kernel.org +MIME-Version: 1.0 +Content-Type: text/plain; charset="utf-8" +Content-Transfer-Encoding: 7bit + +From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> + +When dccps_hc_tx_ccid is freed, ccid timers may still trigger. The reason +del_timer_sync can't be used is because this relies on keeping a reference +to struct sock. But as we keep a pointer to dccps_hc_tx_ccid and free that +during disconnect, the timer should really belong to struct dccp_sock. + +This addresses CVE-2020-16119. + +Fixes: 839a6094140a (net: dccp: Convert timers to use timer_setup()) +Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> +Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> +Acked-bd: Richard Sailer <richard_siegfried@systemli.org> +--- + include/linux/dccp.h | 2 ++ + net/dccp/ccids/ccid2.c | 32 +++++++++++++++++++------------- + net/dccp/ccids/ccid3.c | 30 ++++++++++++++++++++---------- + 3 files changed, 41 insertions(+), 23 deletions(-) + +diff --git a/include/linux/dccp.h b/include/linux/dccp.h +index 07e547c02fd8..504afa1a4be6 100644 +--- a/include/linux/dccp.h ++++ b/include/linux/dccp.h +@@ -259,6 +259,7 @@ struct dccp_ackvec; + * @dccps_sync_scheduled - flag which signals "send out-of-band message soon" + * @dccps_xmitlet - tasklet scheduled by the TX CCID to dequeue data packets + * @dccps_xmit_timer - used by the TX CCID to delay sending (rate-based pacing) ++ * @dccps_ccid_timer - used by the CCIDs + * @dccps_syn_rtt - RTT sample from Request/Response exchange (in usecs) + */ + struct dccp_sock { +@@ -303,6 +304,7 @@ struct dccp_sock { + __u8 dccps_sync_scheduled:1; + struct tasklet_struct dccps_xmitlet; + struct timer_list dccps_xmit_timer; ++ struct timer_list dccps_ccid_timer; + }; + + static inline struct dccp_sock *dccp_sk(const struct sock *sk) +diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c +index 3da1f77bd039..dbca1f1e2449 100644 +--- a/net/dccp/ccids/ccid2.c ++++ b/net/dccp/ccids/ccid2.c +@@ -126,21 +126,26 @@ static void dccp_tasklet_schedule(struct sock *sk) + + static void ccid2_hc_tx_rto_expire(struct timer_list *t) + { +- struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); +- struct sock *sk = hc->sk; +- const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); ++ struct dccp_sock *dp = from_timer(dp, t, dccps_ccid_timer); ++ struct sock *sk = (struct sock *)dp; ++ struct ccid2_hc_tx_sock *hc; ++ bool sender_was_blocked; + + bh_lock_sock(sk); ++ ++ if (inet_sk_state_load(sk) == DCCP_CLOSED) ++ goto out; ++ ++ hc = ccid_priv(dp->dccps_hc_tx_ccid); ++ sender_was_blocked = ccid2_cwnd_network_limited(hc); ++ + if (sock_owned_by_user(sk)) { +- sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + HZ / 5); + goto out; + } + + ccid2_pr_debug("RTO_EXPIRE\n"); + +- if (sk->sk_state == DCCP_CLOSED) +- goto out; +- + /* back-off timer */ + hc->tx_rto <<= 1; + if (hc->tx_rto > DCCP_RTO_MAX) +@@ -166,7 +171,7 @@ static void ccid2_hc_tx_rto_expire(struct timer_list *t) + if (sender_was_blocked) + dccp_tasklet_schedule(sk); + /* restart backed-off timer */ +- sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); + out: + bh_unlock_sock(sk); + sock_put(sk); +@@ -330,7 +335,7 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) + } + #endif + +- sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); + + #ifdef CONFIG_IP_DCCP_CCID2_DEBUG + do { +@@ -700,9 +705,9 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) + + /* restart RTO timer if not all outstanding data has been acked */ + if (hc->tx_pipe == 0) +- sk_stop_timer(sk, &hc->tx_rtotimer); ++ sk_stop_timer(sk, &dp->dccps_ccid_timer); + else +- sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); + done: + /* check if incoming Acks allow pending packets to be sent */ + if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) +@@ -737,17 +742,18 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) + hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32; + hc->tx_cwnd_used = 0; + hc->sk = sk; +- timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0); ++ timer_setup(&dp->dccps_ccid_timer, ccid2_hc_tx_rto_expire, 0); + INIT_LIST_HEAD(&hc->tx_av_chunks); + return 0; + } + + static void ccid2_hc_tx_exit(struct sock *sk) + { ++ struct dccp_sock *dp = dccp_sk(sk); + struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); + int i; + +- sk_stop_timer(sk, &hc->tx_rtotimer); ++ sk_stop_timer(sk, &dp->dccps_ccid_timer); + + for (i = 0; i < hc->tx_seqbufc; i++) + kfree(hc->tx_seqbuf[i]); +diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c +index b9ee1a4a8955..685f4d046c0d 100644 +--- a/net/dccp/ccids/ccid3.c ++++ b/net/dccp/ccids/ccid3.c +@@ -184,17 +184,24 @@ static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc, + + static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) + { +- struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer); +- struct sock *sk = hc->sk; ++ struct dccp_sock *dp = from_timer(dp, t, dccps_ccid_timer); ++ struct ccid3_hc_tx_sock *hc; ++ struct sock *sk = (struct sock *)dp; + unsigned long t_nfb = USEC_PER_SEC / 5; + + bh_lock_sock(sk); ++ ++ if (inet_sk_state_load(sk) == DCCP_CLOSED) ++ goto out; ++ + if (sock_owned_by_user(sk)) { + /* Try again later. */ + /* XXX: set some sensible MIB */ + goto restart_timer; + } + ++ hc = ccid_priv(dp->dccps_hc_tx_ccid); ++ + ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk, + ccid3_tx_state_name(hc->tx_state)); + +@@ -250,8 +257,8 @@ static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) + t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); + + restart_timer: +- sk_reset_timer(sk, &hc->tx_no_feedback_timer, +- jiffies + usecs_to_jiffies(t_nfb)); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, ++ jiffies + usecs_to_jiffies(t_nfb)); + out: + bh_unlock_sock(sk); + sock_put(sk); +@@ -280,7 +287,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) + return -EBADMSG; + + if (hc->tx_state == TFRC_SSTATE_NO_SENT) { +- sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, (jiffies + + usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); + hc->tx_last_win_count = 0; + hc->tx_t_last_win_count = now; +@@ -354,6 +361,7 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len) + static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) + { + struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); ++ struct dccp_sock *dp = dccp_sk(sk); + struct tfrc_tx_hist_entry *acked; + ktime_t now; + unsigned long t_nfb; +@@ -420,7 +428,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) + (unsigned int)(hc->tx_x >> 6)); + + /* unschedule no feedback timer */ +- sk_stop_timer(sk, &hc->tx_no_feedback_timer); ++ sk_stop_timer(sk, &dp->dccps_ccid_timer); + + /* + * As we have calculated new ipi, delta, t_nom it is possible +@@ -445,8 +453,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) + "expire in %lu jiffies (%luus)\n", + dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); + +- sk_reset_timer(sk, &hc->tx_no_feedback_timer, +- jiffies + usecs_to_jiffies(t_nfb)); ++ sk_reset_timer(sk, &dp->dccps_ccid_timer, ++ jiffies + usecs_to_jiffies(t_nfb)); + } + + static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, +@@ -488,21 +496,23 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, + + static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) + { ++ struct dccp_sock *dp = dccp_sk(sk); + struct ccid3_hc_tx_sock *hc = ccid_priv(ccid); + + hc->tx_state = TFRC_SSTATE_NO_SENT; + hc->tx_hist = NULL; + hc->sk = sk; +- timer_setup(&hc->tx_no_feedback_timer, ++ timer_setup(&dp->dccps_ccid_timer, + ccid3_hc_tx_no_feedback_timer, 0); + return 0; + } + + static void ccid3_hc_tx_exit(struct sock *sk) + { ++ struct dccp_sock *dp = dccp_sk(sk); + struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); + +- sk_stop_timer(sk, &hc->tx_no_feedback_timer); ++ sk_stop_timer(sk, &dp->dccps_ccid_timer); + tfrc_tx_hist_purge(&hc->tx_hist); + } + +-- +2.25.1 + + +From MAILER-DAEMON Wed Oct 14 16:34:37 2020 +From: Kleber Sacilotto de Souza <kleber.souza@canonical.com> +To: netdev@vger.kernel.org +Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>, "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Thadeu Lima de Souza Cascardo <cascardo@canonical.com>, "Gustavo A. R. Silva" <gustavoars@kernel.org>, "Alexander A. Klimov" <grandmaster@al2klimov.de>, Kees Cook <keescook@chromium.org>, Eric Dumazet <edumazet@google.com>, Alexey Kodanev <alexey.kodanev@oracle.com>, dccp@vger.kernel.org, linux-kernel@vger.kernel.org +Subject: [PATCH 2/2] Revert "dccp: don't free ccid2_hc_tx_sock struct in dccp_disconnect()" +Date: Tue, 13 Oct 2020 19:18:49 +0200 +Message-Id: <20201013171849.236025-3-kleber.souza@canonical.com> +In-Reply-To: <20201013171849.236025-1-kleber.souza@canonical.com> +References: <20201013171849.236025-1-kleber.souza@canonical.com> +List-ID: <linux-kernel.vger.kernel.org> +X-Mailing-List: linux-kernel@vger.kernel.org +MIME-Version: 1.0 +Content-Type: text/plain; charset="utf-8" +Content-Transfer-Encoding: 7bit + +From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> + +This reverts commit 2677d20677314101293e6da0094ede7b5526d2b1. + +This fixes an issue that after disconnect, dccps_hc_tx_ccid will still be +kept, allowing the socket to be reused as a listener socket, and the cloned +socket will free its dccps_hc_tx_ccid, leading to a later use after free, +when the listener socket is closed. + +This addresses CVE-2020-16119. + +Fixes: 2677d2067731 (dccp: don't free ccid2_hc_tx_sock struct in dccp_disconnect()) +Reported-by: Hadar Manor +Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> +Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> +Acked-by: Richard Sailer <richard_siegfried@systemli.org> +--- + net/dccp/proto.c | 2 ++ + 1 file changed, 2 insertions(+) + +diff --git a/net/dccp/proto.c b/net/dccp/proto.c +index 6d705d90c614..359e848dba6c 100644 +--- a/net/dccp/proto.c ++++ b/net/dccp/proto.c +@@ -279,7 +279,9 @@ int dccp_disconnect(struct sock *sk, int flags) + + dccp_clear_xmit_timers(sk); + ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); ++ ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); + dp->dccps_hc_rx_ccid = NULL; ++ dp->dccps_hc_tx_ccid = NULL; + + __skb_queue_purge(&sk->sk_receive_queue); + __skb_queue_purge(&sk->sk_write_queue); +-- +2.25.1 + + |