From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> This fixes the following trace by reworking the locking of l2cap_conn so instead of only locking when changing the chan_l list this promotes chan_lock to a general lock of l2cap_conn so whenever it is being held it would prevents the likes of l2cap_conn_del to run: list_del corruption, ffff888021297e00->prev is LIST_POISON2 (dead000000000122) ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:61! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 UID: 0 PID: 5896 Comm: syz-executor213 Not tainted 6.14.0-rc1-next-20250204-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 RIP: 0010:__list_del_entry_valid_or_report+0x12c/0x190 lib/list_debug.c:59 Code: 8c 4c 89 fe 48 89 da e8 32 8c 37 fc 90 0f 0b 48 89 df e8 27 9f 14 fd 48 c7 c7 a0 c0 60 8c 4c 89 fe 48 89 da e8 15 8c 37 fc 90 <0f> 0b 4c 89 e7 e8 0a 9f 14 fd 42 80 3c 2b 00 74 08 4c 89 e7 e8 cb RSP: 0018:ffffc90003f6f998 EFLAGS: 00010246 RAX: 000000000000004e RBX: dead000000000122 RCX: 01454d423f7fbf00 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff819f077c R09: 1ffff920007eded0 R10: dffffc0000000000 R11: fffff520007eded1 R12: dead000000000122 R13: dffffc0000000000 R14: ffff8880352248d8 R15: ffff888021297e00 FS: 00007f7ace6686c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7aceeeb1d0 CR3: 000000003527c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __list_del_entry_valid include/linux/list.h:124 [inline] __list_del_entry include/linux/list.h:215 [inline] list_del_rcu include/linux/rculist.h:168 [inline] hci_chan_del+0x70/0x1b0 net/bluetooth/hci_conn.c:2858 l2cap_conn_free net/bluetooth/l2cap_core.c:1816 [inline] kref_put include/linux/kref.h:65 [inline] l2cap_conn_put+0x70/0xe0 net/bluetooth/l2cap_core.c:1830 l2cap_sock_shutdown+0xa8a/0x1020 net/bluetooth/l2cap_sock.c:1377 l2cap_sock_release+0x79/0x1d0 net/bluetooth/l2cap_sock.c:1416 __sock_release net/socket.c:642 [inline] sock_close+0xbc/0x240 net/socket.c:1393 __fput+0x3e9/0x9f0 fs/file_table.c:448 task_work_run+0x24f/0x310 kernel/task_work.c:227 ptrace_notify+0x2d2/0x380 kernel/signal.c:2522 ptrace_report_syscall include/linux/ptrace.h:415 [inline] ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline] syscall_exit_work+0xc7/0x1d0 kernel/entry/common.c:173 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline] syscall_exit_to_user_mode+0x24a/0x340 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7aceeaf449 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7ace668218 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: fffffffffffffffc RBX: 00007f7acef39328 RCX: 00007f7aceeaf449 RDX: 000000000000000e RSI: 0000000020000100 RDI: 0000000000000004 RBP: 00007f7acef39320 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000004 R14: 00007f7ace668670 R15: 000000000000000b </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:__list_del_entry_valid_or_report+0x12c/0x190 lib/list_debug.c:59 Code: 8c 4c 89 fe 48 89 da e8 32 8c 37 fc 90 0f 0b 48 89 df e8 27 9f 14 fd 48 c7 c7 a0 c0 60 8c 4c 89 fe 48 89 da e8 15 8c 37 fc 90 <0f> 0b 4c 89 e7 e8 0a 9f 14 fd 42 80 3c 2b 00 74 08 4c 89 e7 e8 cb RSP: 0018:ffffc90003f6f998 EFLAGS: 00010246 RAX: 000000000000004e RBX: dead000000000122 RCX: 01454d423f7fbf00 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff819f077c R09: 1ffff920007eded0 R10: dffffc0000000000 R11: fffff520007eded1 R12: dead000000000122 R13: dffffc0000000000 R14: ffff8880352248d8 R15: ffff888021297e00 FS: 00007f7ace6686c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7acef05b08 CR3: 000000003527c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Reported-by: syzbot+10bd8fe6741eedd2be2e@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 6ab54a717189 ("Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd") Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> --- include/net/bluetooth/l2cap.h | 2 +- net/bluetooth/l2cap_core.c | 123 +++++++++++----------------------- net/bluetooth/l2cap_sock.c | 4 +- 3 files changed, 41 insertions(+), 88 deletions(-) diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h index d9c767cf773d..6b90cfa15d88 100644 --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -668,7 +668,7 @@ struct l2cap_conn { struct l2cap_chan *smp; struct list_head chan_l; - struct mutex chan_lock; + struct mutex lock; struct kref ref; struct list_head users; }; diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index adb8c33ac595..5eedd6611f6c 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -119,7 +119,6 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, { struct l2cap_chan *c; - mutex_lock(&conn->chan_lock); c = __l2cap_get_chan_by_scid(conn, cid); if (c) { /* Only lock if chan reference is not 0 */ @@ -127,7 +126,6 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, if (c) l2cap_chan_lock(c); } - mutex_unlock(&conn->chan_lock); return c; } @@ -140,7 +138,6 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn, { struct l2cap_chan *c; - mutex_lock(&conn->chan_lock); c = __l2cap_get_chan_by_dcid(conn, cid); if (c) { /* Only lock if chan reference is not 0 */ @@ -148,7 +145,6 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn, if (c) l2cap_chan_lock(c); } - mutex_unlock(&conn->chan_lock); return c; } @@ -418,7 +414,7 @@ static void l2cap_chan_timeout(struct work_struct *work) if (!conn) return; - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); /* __set_chan_timer() calls l2cap_chan_hold(chan) while scheduling * this work. No need to call l2cap_chan_hold(chan) here again. */ @@ -439,7 +435,7 @@ static void l2cap_chan_timeout(struct work_struct *work) l2cap_chan_unlock(chan); l2cap_chan_put(chan); - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); } struct l2cap_chan *l2cap_chan_create(void) @@ -641,9 +637,9 @@ void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) { - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); __l2cap_chan_add(conn, chan); - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); } void l2cap_chan_del(struct l2cap_chan *chan, int err) @@ -731,9 +727,9 @@ void l2cap_chan_list(struct l2cap_conn *conn, l2cap_chan_func_t func, if (!conn) return; - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); __l2cap_chan_list(conn, func, data); - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); } EXPORT_SYMBOL_GPL(l2cap_chan_list); @@ -745,7 +741,7 @@ static void l2cap_conn_update_id_addr(struct work_struct *work) struct hci_conn *hcon = conn->hcon; struct l2cap_chan *chan; - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); list_for_each_entry(chan, &conn->chan_l, list) { l2cap_chan_lock(chan); @@ -754,7 +750,7 @@ static void l2cap_conn_update_id_addr(struct work_struct *work) l2cap_chan_unlock(chan); } - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); } static void l2cap_chan_le_connect_reject(struct l2cap_chan *chan) @@ -1507,8 +1503,6 @@ static void l2cap_conn_start(struct l2cap_conn *conn) BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); - list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) { l2cap_chan_lock(chan); @@ -1577,8 +1571,6 @@ static void l2cap_conn_start(struct l2cap_conn *conn) l2cap_chan_unlock(chan); } - - mutex_unlock(&conn->chan_lock); } static void l2cap_le_conn_ready(struct l2cap_conn *conn) @@ -1624,7 +1616,7 @@ static void l2cap_conn_ready(struct l2cap_conn *conn) if (hcon->type == ACL_LINK) l2cap_request_info(conn); - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); list_for_each_entry(chan, &conn->chan_l, list) { @@ -1642,7 +1634,7 @@ static void l2cap_conn_ready(struct l2cap_conn *conn) l2cap_chan_unlock(chan); } - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); if (hcon->type == LE_LINK) l2cap_le_conn_ready(conn); @@ -1657,14 +1649,10 @@ static void l2cap_conn_unreliable(struct l2cap_conn *conn, int err) BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); - list_for_each_entry(chan, &conn->chan_l, list) { if (test_bit(FLAG_FORCE_RELIABLE, &chan->flags)) l2cap_chan_set_err(chan, err); } - - mutex_unlock(&conn->chan_lock); } static void l2cap_info_timeout(struct work_struct *work) @@ -1675,7 +1663,9 @@ static void l2cap_info_timeout(struct work_struct *work) conn->info_state |= L2CAP_INFO_FEAT_MASK_REQ_DONE; conn->info_ident = 0; + mutex_lock(&conn->lock); l2cap_conn_start(conn); + mutex_unlock(&conn->lock); } /* @@ -1767,6 +1757,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err) BT_DBG("hcon %p conn %p, err %d", hcon, conn, err); + mutex_lock(&conn->lock); + kfree_skb(conn->rx_skb); skb_queue_purge(&conn->pending_rx); @@ -1785,8 +1777,6 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err) /* Force the connection to be immediately dropped */ hcon->disc_timeout = 0; - mutex_lock(&conn->chan_lock); - /* Kill channels */ list_for_each_entry_safe(chan, l, &conn->chan_l, list) { l2cap_chan_hold(chan); @@ -1800,12 +1790,11 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err) l2cap_chan_put(chan); } - mutex_unlock(&conn->chan_lock); - if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT) cancel_delayed_work_sync(&conn->info_timer); hcon->l2cap_data = NULL; + mutex_unlock(&conn->lock); l2cap_conn_put(conn); } @@ -2924,8 +2913,6 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb) BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); - list_for_each_entry(chan, &conn->chan_l, list) { if (chan->chan_type != L2CAP_CHAN_RAW) continue; @@ -2940,8 +2927,6 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb) if (chan->ops->recv(chan, nskb)) kfree_skb(nskb); } - - mutex_unlock(&conn->chan_lock); } /* ---- L2CAP signalling commands ---- */ @@ -3960,7 +3945,6 @@ static void l2cap_connect(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, goto response; } - mutex_lock(&conn->chan_lock); l2cap_chan_lock(pchan); /* Check if the ACL is secure enough (if not SDP) */ @@ -4067,7 +4051,6 @@ static void l2cap_connect(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, } l2cap_chan_unlock(pchan); - mutex_unlock(&conn->chan_lock); l2cap_chan_put(pchan); } @@ -4106,27 +4089,19 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn, BT_DBG("dcid 0x%4.4x scid 0x%4.4x result 0x%2.2x status 0x%2.2x", dcid, scid, result, status); - mutex_lock(&conn->chan_lock); - if (scid) { chan = __l2cap_get_chan_by_scid(conn, scid); - if (!chan) { - err = -EBADSLT; - goto unlock; - } + if (!chan) + return -EBADSLT; } else { chan = __l2cap_get_chan_by_ident(conn, cmd->ident); - if (!chan) { - err = -EBADSLT; - goto unlock; - } + if (!chan) + return -EBADSLT; } chan = l2cap_chan_hold_unless_zero(chan); - if (!chan) { - err = -EBADSLT; - goto unlock; - } + if (!chan) + return -EBADSLT; err = 0; @@ -4164,9 +4139,6 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn, l2cap_chan_unlock(chan); l2cap_chan_put(chan); -unlock: - mutex_unlock(&conn->chan_lock); - return err; } @@ -4454,11 +4426,7 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, chan->ops->set_shutdown(chan); - l2cap_chan_unlock(chan); - mutex_lock(&conn->chan_lock); - l2cap_chan_lock(chan); l2cap_chan_del(chan, ECONNRESET); - mutex_unlock(&conn->chan_lock); chan->ops->close(chan); @@ -4495,11 +4463,7 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, return 0; } - l2cap_chan_unlock(chan); - mutex_lock(&conn->chan_lock); - l2cap_chan_lock(chan); l2cap_chan_del(chan, 0); - mutex_unlock(&conn->chan_lock); chan->ops->close(chan); @@ -4697,13 +4661,9 @@ static int l2cap_le_connect_rsp(struct l2cap_conn *conn, BT_DBG("dcid 0x%4.4x mtu %u mps %u credits %u result 0x%2.2x", dcid, mtu, mps, credits, result); - mutex_lock(&conn->chan_lock); - chan = __l2cap_get_chan_by_ident(conn, cmd->ident); - if (!chan) { - err = -EBADSLT; - goto unlock; - } + if (!chan) + return -EBADSLT; err = 0; @@ -4751,9 +4711,6 @@ static int l2cap_le_connect_rsp(struct l2cap_conn *conn, l2cap_chan_unlock(chan); -unlock: - mutex_unlock(&conn->chan_lock); - return err; } @@ -4865,7 +4822,6 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn, goto response; } - mutex_lock(&conn->chan_lock); l2cap_chan_lock(pchan); if (!smp_sufficient_security(conn->hcon, pchan->sec_level, @@ -4931,7 +4887,6 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn, response_unlock: l2cap_chan_unlock(pchan); - mutex_unlock(&conn->chan_lock); l2cap_chan_put(pchan); if (result == L2CAP_CR_PEND) @@ -5065,7 +5020,6 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn, goto response; } - mutex_lock(&conn->chan_lock); l2cap_chan_lock(pchan); if (!smp_sufficient_security(conn->hcon, pchan->sec_level, @@ -5140,7 +5094,6 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn, unlock: l2cap_chan_unlock(pchan); - mutex_unlock(&conn->chan_lock); l2cap_chan_put(pchan); response: @@ -5177,8 +5130,6 @@ static inline int l2cap_ecred_conn_rsp(struct l2cap_conn *conn, BT_DBG("mtu %u mps %u credits %u result 0x%4.4x", mtu, mps, credits, result); - mutex_lock(&conn->chan_lock); - cmd_len -= sizeof(*rsp); list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) { @@ -5264,8 +5215,6 @@ static inline int l2cap_ecred_conn_rsp(struct l2cap_conn *conn, l2cap_chan_unlock(chan); } - mutex_unlock(&conn->chan_lock); - return err; } @@ -5378,8 +5327,6 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn, if (cmd_len < sizeof(*rej)) return -EPROTO; - mutex_lock(&conn->chan_lock); - chan = __l2cap_get_chan_by_ident(conn, cmd->ident); if (!chan) goto done; @@ -5394,7 +5341,6 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn, l2cap_chan_put(chan); done: - mutex_unlock(&conn->chan_lock); return 0; } @@ -6849,8 +6795,12 @@ static void process_pending_rx(struct work_struct *work) BT_DBG(""); + mutex_lock(&conn->lock); + while ((skb = skb_dequeue(&conn->pending_rx))) l2cap_recv_frame(conn, skb); + + mutex_unlock(&conn->lock); } static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon) @@ -6889,7 +6839,7 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon) conn->local_fixed_chan |= L2CAP_FC_SMP_BREDR; mutex_init(&conn->ident_lock); - mutex_init(&conn->chan_lock); + mutex_init(&conn->lock); INIT_LIST_HEAD(&conn->chan_l); INIT_LIST_HEAD(&conn->users); @@ -7080,7 +7030,7 @@ int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid, } } - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); l2cap_chan_lock(chan); if (cid && __l2cap_get_chan_by_dcid(conn, cid)) { @@ -7121,7 +7071,7 @@ int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid, chan_unlock: l2cap_chan_unlock(chan); - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); done: hci_dev_unlock(hdev); hci_dev_put(hdev); @@ -7333,7 +7283,7 @@ static void l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt) BT_DBG("conn %p status 0x%2.2x encrypt %u", conn, status, encrypt); - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); list_for_each_entry(chan, &conn->chan_l, list) { l2cap_chan_lock(chan); @@ -7407,7 +7357,7 @@ static void l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt) l2cap_chan_unlock(chan); } - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); } /* Append fragment into frame respecting the maximum len of rx_skb */ @@ -7506,6 +7456,8 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) BT_DBG("conn %p len %u flags 0x%x", conn, skb->len, flags); + mutex_lock(&conn->lock); + switch (flags) { case ACL_START: case ACL_START_NO_FLUSH: @@ -7530,7 +7482,7 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) if (len == skb->len) { /* Complete frame received */ l2cap_recv_frame(conn, skb); - return; + goto unlock; } BT_DBG("Start: total len %d, frag len %u", len, skb->len); @@ -7592,10 +7544,11 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) break; } - l2cap_conn_put(conn); - drop: kfree_skb(skb); +unlock: + mutex_unlock(&conn->lock); + l2cap_conn_put(conn); } static struct hci_cb l2cap_cb = { diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 46ea0bee2259..831ab9b97001 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1366,14 +1366,14 @@ static int l2cap_sock_shutdown(struct socket *sock, int how) if (conn) /* mutex lock must be taken before l2cap_chan_lock() */ - mutex_lock(&conn->chan_lock); + mutex_lock(&conn->lock); l2cap_chan_lock(chan); l2cap_chan_close(chan, 0); l2cap_chan_unlock(chan); if (conn) { - mutex_unlock(&conn->chan_lock); + mutex_unlock(&conn->lock); l2cap_conn_put(conn); } -- 2.48.1