From: Samuel Page <sam@bynar.io> stable inclusion from stable-v5.10.261 commit 055663d21dc4336f67933ab26bef3c5934be6324 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16741 CVE: CVE-2026-64450 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 2b66974a1b6134a4bbc3bfed181f7418f688eb54 upstream. A broadcast PROTOCOL/STATE_MSG can carry a Gap ACK blocks record in its data area. tipc_get_gap_ack_blks() only verifies that the record's len field is self-consistent with its ugack_cnt/bgack_cnt counts (sz == struct_size(p, gacks, ugack_cnt + bgack_cnt)); it does not check that the record actually fits in the message data area, msg_data_sz(). The unicast caller tipc_link_proto_rcv() bounds it ("if (glen > dlen) break;"), but the broadcast caller tipc_bcast_sync_rcv() discards the returned size, so tipc_link_advance_transmq() copies the record off the receive skb with an attacker-controlled count: this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt), GFP_ATOMIC); A TIPC neighbour that negotiated TIPC_GAP_ACK_BLOCK triggers it with one ordinary broadcast STATE_MSG (msg_bc_ack_invalid() clear), sized so its data area is short, carrying a Gap ACK record with len = 0x400, bgack_cnt = 0xff and ugack_cnt = 0. len then equals struct_size(p, gacks, 255), so the consistency check passes and ga is non-NULL; kmemdup() reads struct_size(ga, gacks, 255) = 1024 bytes out of the much smaller skb: BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x48/0x60 Read of size 1024 at addr ffff0000c7030d38 by task poc864/69 Call trace: kmemdup_noprof+0x48/0x60 tipc_link_advance_transmq+0x86c/0xb80 tipc_link_bc_ack_rcv+0x19c/0x1e0 tipc_bcast_sync_rcv+0x1c4/0x2c4 tipc_rcv+0x85c/0x1340 tipc_l2_rcv_msg+0xac/0x104 The buggy address belongs to the object at ffff0000c7030d00 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 56 bytes inside of allocated 704-byte region [ffff0000c7030d00, ffff0000c7030fc0) The copied-out bytes are subsequently consumed as gap/ack values, but the read is already out of bounds at the kmemdup() regardless of how they are used. The unicast STATE path drops such a message: "if (glen > dlen) break;" skips the rest of STATE_MSG handling and the skb is freed. Make the broadcast path drop it too. tipc_bcast_sync_rcv() now bounds the record against msg_data_sz() and, when it does not fit, reports it back through tipc_node_bc_sync_rcv() to tipc_rcv() so the skb is discarded rather than processed. ga is not cleared on this path: ga == NULL already means "legacy peer without Selective ACK", a distinct legitimate state. Fixes: d7626b5acff9 ("tipc: introduce Gap ACK blocks for broadcast link") Cc: stable@vger.kernel.org Signed-off-by: Samuel Page <sam@bynar.io> Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech> Link: https://patch.msgid.link/20260625143815.1525412-1-sam@bynar.io Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- net/tipc/bcast.c | 22 ++++++++++++++-------- net/tipc/bcast.h | 2 +- net/tipc/node.c | 15 ++++++++++++--- 3 files changed, 27 insertions(+), 12 deletions(-) diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c index 593846d25214..631b98097dba 100644 --- a/net/tipc/bcast.c +++ b/net/tipc/bcast.c @@ -497,12 +497,13 @@ void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l, */ int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l, struct tipc_msg *hdr, - struct sk_buff_head *retrq) + struct sk_buff_head *retrq, bool *valid) { struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq; struct tipc_gap_ack_blks *ga; struct sk_buff_head xmitq; int rc = 0; + u16 glen; __skb_queue_head_init(&xmitq); @@ -510,13 +511,18 @@ int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l, if (msg_type(hdr) != STATE_MSG) { tipc_link_bc_init_rcv(l, hdr); } else if (!msg_bc_ack_invalid(hdr)) { - tipc_get_gap_ack_blks(&ga, l, hdr, false); - if (!sysctl_tipc_bc_retruni) - retrq = &xmitq; - rc = tipc_link_bc_ack_rcv(l, msg_bcast_ack(hdr), - msg_bc_gap(hdr), ga, &xmitq, - retrq); - rc |= tipc_link_bc_sync_rcv(l, hdr, &xmitq); + glen = tipc_get_gap_ack_blks(&ga, l, hdr, false); + if (glen > msg_data_sz(hdr)) { + /* Malformed Gap ACK blocks; caller drops the msg */ + *valid = false; + } else { + if (!sysctl_tipc_bc_retruni) + retrq = &xmitq; + rc = tipc_link_bc_ack_rcv(l, msg_bcast_ack(hdr), + msg_bc_gap(hdr), ga, &xmitq, + retrq); + rc |= tipc_link_bc_sync_rcv(l, hdr, &xmitq); + } } tipc_bcast_unlock(net); diff --git a/net/tipc/bcast.h b/net/tipc/bcast.h index 2d9352dc7b0e..55d17b5413e1 100644 --- a/net/tipc/bcast.h +++ b/net/tipc/bcast.h @@ -97,7 +97,7 @@ void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l, struct tipc_msg *hdr); int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l, struct tipc_msg *hdr, - struct sk_buff_head *retrq); + struct sk_buff_head *retrq, bool *valid); int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg, struct tipc_link *bcl); int tipc_nl_bc_link_set(struct net *net, struct nlattr *attrs[]); diff --git a/net/tipc/node.c b/net/tipc/node.c index 5f6866407be5..8e52b2995817 100644 --- a/net/tipc/node.c +++ b/net/tipc/node.c @@ -1804,12 +1804,15 @@ static void tipc_node_mcast_rcv(struct tipc_node *n) } static void tipc_node_bc_sync_rcv(struct tipc_node *n, struct tipc_msg *hdr, - int bearer_id, struct sk_buff_head *xmitq) + int bearer_id, struct sk_buff_head *xmitq, + bool *valid) { struct tipc_link *ucl; int rc; - rc = tipc_bcast_sync_rcv(n->net, n->bc_entry.link, hdr, xmitq); + rc = tipc_bcast_sync_rcv(n->net, n->bc_entry.link, hdr, xmitq, valid); + if (!*valid) + return; if (rc & TIPC_LINK_DOWN_EVT) { tipc_node_reset_links(n); @@ -2111,12 +2114,18 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b) /* Ensure broadcast reception is in synch with peer's send state */ if (unlikely(usr == LINK_PROTOCOL)) { + bool valid = true; + if (unlikely(skb_linearize(skb))) { tipc_node_put(n); goto discard; } hdr = buf_msg(skb); - tipc_node_bc_sync_rcv(n, hdr, bearer_id, &xmitq); + tipc_node_bc_sync_rcv(n, hdr, bearer_id, &xmitq, &valid); + if (!valid) { + tipc_node_put(n); + goto discard; + } } else if (unlikely(tipc_link_acked(n->bc_entry.link) != bc_ack)) { tipc_bcast_ack_rcv(net, n->bc_entry.link, hdr); } -- 2.43.0