kernel/linux.git/drivers/net/amt.c, branch v6.6.150

amt: make the head writable before rewriting the L2 header

2026-08-03T09:15:21+00:00

[ Upstream commit 53969d704fa5b7c1751e277fac96bfc22b435eac ] amt_multicast_data_handler(), amt_membership_query_handler() and amt_update_handler() rewrite the ethernet header of the decapsulated skb in place (eth->h_proto, eth->h_dest and, for the query, also eth->h_source) before handing it up the stack. The skb head may be shared, for example when a packet tap has cloned it on the underlay interface, so writing through it corrupts the other reader's copy. Call skb_cow_head() before the rewrite so the head is private. It is placed before the pointers into the head are (re-)derived, so a reallocation caused by the copy is picked up by those derivations. Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface") Signed-off-by: Michael Bommarito Reviewed-by: Simon Horman Reviewed-by: Taehee Yoo Link: https://patch.msgid.link/20260711151934.2955226-3-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

amt: re-read skb header pointers after every pull

2026-08-03T09:15:21+00:00

[ Upstream commit 3656a79f94c471827a08f2cacce5f94ad5e52c24 ] Several AMT receive and transmit paths cache a pointer into the skb head (ip_hdr(), ipv6_hdr(), eth_hdr() or the AMT message header) and then call a helper that can reallocate that head before the cached pointer is used again. pskb_may_pull(), ip_mc_may_pull(), ipv6_mc_may_pull(), iptunnel_pull_header(), ip_mc_check_igmp() and ipv6_mc_check_mld() can all free the old head and move the data, so a pointer taken before the call dangles afterwards and the later access is a use-after-free of the freed head. The affected sites are: amt_rcv() caches ip_hdr() before amt_parse_type() pulls, then reads iph->saddr. amt_dev_xmit() caches ip_hdr()/ipv6_hdr() before ip_mc_check_igmp()/ ipv6_mc_check_mld() and pskb_may_pull(), then reads the group address. amt_multicast_data_handler() caches eth_hdr() before pskb_may_pull(), then writes the L2 header. amt_membership_query_handler() caches the AMT header, the outer and inner eth_hdr() and ip_hdr() before iptunnel_pull_header() and several pulls, then reads and writes them. amt_igmpv3_report_handler() and amt_mldv2_report_handler() cache ip_hdr()/ipv6_hdr() and the current group record and read the record count from the report header inside the record loop, across the *_mc_may_pull() calls. amt_update_handler() caches ip_hdr() and the AMT membership-update header before pskb_may_pull(), iptunnel_pull_header(), ip_mc_check_igmp() and the report handler, then reads iph->daddr and amtmu->nonce / amtmu->response_mac. Fix each site by either snapshotting the scalar that is used after the pull before the first pull runs, or re-deriving the header pointer from the skb after the last pull that can move the head. Values that are stable across the pull (source and group address, the response MAC and nonce, the record count, the outer source MAC) are snapshotted; pointers that are written through or read repeatedly are re-derived. Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface") Signed-off-by: Michael Bommarito Reviewed-by: Simon Horman Reviewed-by: Taehee Yoo Link: https://patch.msgid.link/20260711151934.2955226-2-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

amt: fix size calculation in amt_get_size()

2026-07-24T14:03:28+00:00

[ Upstream commit 9e05e91a9a847ed57926414bd7c2c5e54d6c56c6 ] amt_get_size() incorrectly used sizeof(struct iphdr) for the sizes of IFLA_AMT_DISCOVERY_IP, IFLA_AMT_REMOTE_IP, and IFLA_AMT_LOCAL_IP. These attributes contain IPv4 addresses (__be32), not full IP headers. Replace sizeof(struct iphdr) with sizeof(__be32) to avoid over-allocating netlink message space. Fixes: b9022b53adad ("amt: add control plane of amt interface") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260701122329.3562825-1-edumazet@google.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

amt: do not use overwrapped cb area

2024-01-25T23:35:56+00:00

[ Upstream commit bec161add35b478a7746bf58bcdea6faa19129ef ] amt driver uses skb->cb for storing tunnel information. This job is worked before TC layer and then amt driver load tunnel info from skb->cb after TC layer. So, its cb area should not be overwrapped with CB area used by TC. In order to not use cb area used by TC, it skips the biggest cb structure used by TC, which was qdisc_skb_cb. But it's not anymore. Currently, biggest structure of TC's CB is tc_skb_cb. So, it should skip size of tc_skb_cb instead of qdisc_skb_cb. Fixes: ec624fe740b4 ("net/sched: Extend qdisc control block with tc control block") Signed-off-by: Taehee Yoo Acked-by: Paolo Abeni Reviewed-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20240107144241.4169520-1-ap420073@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

amt: remove unnecessary skb pointer check

2022-08-19T23:51:21+00:00

The skb pointer will be checked in kfree_skb(), so remove the outside check. Signed-off-by: Yang Yingliang Reviewed-by: Taehee Yoo Link: https://lore.kernel.org/r/20220818093114.2449179-1-yangyingliang@huawei.com Signed-off-by: Jakub Kicinski

amt: fix typo in comment

2022-07-29T05:21:51+00:00

Correct spelling on 'non-existent' in comment Signed-off-by: Ruffalo Lavoisier Link: https://lore.kernel.org/r/20220728032854.151180-1-RuffaloLavoisier@gmail.com Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2022-07-21T20:03:39+00:00

No conflicts. Signed-off-by: Jakub Kicinski

amt: do not use amt->nr_tunnels outside of lock

2022-07-19T10:37:02+00:00

amt->nr_tunnels is protected by amt->lock. But, amt_request_handler() has been using this variable without the amt->lock. So, it expands context of amt->lock in the amt_request_handler() to protect amt->nr_tunnels variable. Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface") Signed-off-by: Taehee Yoo Signed-off-by: Paolo Abeni

amt: drop unexpected multicast data

2022-07-19T10:37:02+00:00

AMT gateway interface should not receive unexpected multicast data. Multicast data message type should be received after sending an update message, which means all establishment between gateway and relay is finished. So, amt_multicast_data_handler() checks amt->status. Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface") Signed-off-by: Taehee Yoo Signed-off-by: Paolo Abeni

amt: drop unexpected query message

2022-07-19T10:37:02+00:00

AMT gateway interface should not receive unexpected query messages. In order to drop unexpected query messages, it checks nonce. And it also checks ready4 and ready6 variables to drop duplicated messages. Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface") Signed-off-by: Taehee Yoo Signed-off-by: Paolo Abeni