kernel/git/stable/linux.git/net/mctp, branch linux-5.18.y

net: remove noblock parameter from skb_recv_datagram()

2022-06-22T12:28:02+00:00

[ Upstream commit f4b41f062c424209e3939a81e6da022e049a45f2 ] skb_recv_datagram() has two parameters 'flags' and 'noblock' that are merged inside skb_recv_datagram() by 'flags | (noblock ? MSG_DONTWAIT : 0)' As 'flags' may contain MSG_DONTWAIT as value most callers split the 'flags' into 'flags' and 'noblock' with finally obsolete bit operations like this: skb_recv_datagram(sk, flags & ~MSG_DONTWAIT, flags & MSG_DONTWAIT, &rc); And this is not even done consistently with the 'flags' parameter. This patch removes the obsolete and costly splitting into two parameters and only performs bit operations when really needed on the caller side. One missing conversion thankfully reported by kernel test robot. I missed to enable kunit tests to build the mctp code. Reported-by: kernel test robot Signed-off-by: Oliver Hartkopp Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

mctp: defer the kfree of object mdev->addrs

2022-04-26T07:14:47+00:00

The function mctp_unregister() reclaims the device's relevant resource when a netcard detaches. However, a running routine may be unaware of this and cause the use-after-free of the mdev->addrs object. The race condition can be demonstrated below cleanup thread another thread | unregister_netdev() | mctp_sendmsg() ... | ... mctp_unregister() | rt = mctp_route_lookup() ... | mctl_local_output() kfree(mdev->addrs) | ... | saddr = rt->dev->addrs[0]; | An attacker can adopt the (recent provided) mtcpserial driver with pty to fake the device detaching and use the userfaultfd to increase the race success chance (in mctp_sendmsg). The KASan report for such a POC is shown below: [ 86.051955] ================================================================== [ 86.051955] BUG: KASAN: use-after-free in mctp_local_output+0x4e9/0xb7d [ 86.051955] Read of size 1 at addr ffff888005f298c0 by task poc/295 [ 86.051955] [ 86.051955] Call Trace: [ 86.051955] [ 86.051955] dump_stack_lvl+0x33/0x42 [ 86.051955] print_report.cold.13+0xb2/0x6b3 [ 86.051955] ? preempt_schedule_irq+0x57/0x80 [ 86.051955] ? mctp_local_output+0x4e9/0xb7d [ 86.051955] kasan_report+0xa5/0x120 [ 86.051955] ? mctp_local_output+0x4e9/0xb7d [ 86.051955] mctp_local_output+0x4e9/0xb7d [ 86.051955] ? mctp_dev_set_key+0x79/0x79 [ 86.051955] ? copyin+0x38/0x50 [ 86.051955] ? _copy_from_iter+0x1b6/0xf20 [ 86.051955] ? sysvec_apic_timer_interrupt+0x97/0xb0 [ 86.051955] ? asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 86.051955] ? mctp_local_output+0x1/0xb7d [ 86.051955] mctp_sendmsg+0x64d/0xdb0 [ 86.051955] ? mctp_sk_close+0x20/0x20 [ 86.051955] ? __fget_light+0x2fd/0x4f0 [ 86.051955] ? mctp_sk_close+0x20/0x20 [ 86.051955] sock_sendmsg+0xdd/0x110 [ 86.051955] __sys_sendto+0x1cc/0x2a0 [ 86.051955] ? __ia32_sys_getpeername+0xa0/0xa0 [ 86.051955] ? new_sync_write+0x335/0x550 [ 86.051955] ? alloc_file+0x22f/0x500 [ 86.051955] ? __ip_do_redirect+0x820/0x1820 [ 86.051955] ? vfs_write+0x44d/0x7b0 [ 86.051955] ? vfs_write+0x44d/0x7b0 [ 86.051955] ? fput_many+0x15/0x120 [ 86.051955] ? ksys_write+0x155/0x1b0 [ 86.051955] ? __ia32_sys_read+0xa0/0xa0 [ 86.051955] __x64_sys_sendto+0xd8/0x1b0 [ 86.051955] ? exit_to_user_mode_prepare+0x2f/0x120 [ 86.051955] ? syscall_exit_to_user_mode+0x12/0x20 [ 86.051955] do_syscall_64+0x3a/0x80 [ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 86.051955] RIP: 0033:0x7f82118a56b3 [ 86.051955] RSP: 002b:00007ffdb154b110 EFLAGS: 00000293 ORIG_RAX: 000000000000002c [ 86.051955] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f82118a56b3 [ 86.051955] RDX: 0000000000000010 RSI: 00007f8211cd4000 RDI: 0000000000000007 [ 86.051955] RBP: 00007ffdb154c1d0 R08: 00007ffdb154b164 R09: 000000000000000c [ 86.051955] R10: 0000000000000000 R11: 0000000000000293 R12: 000055d779800db0 [ 86.051955] R13: 00007ffdb154c2b0 R14: 0000000000000000 R15: 0000000000000000 [ 86.051955] [ 86.051955] [ 86.051955] Allocated by task 295: [ 86.051955] kasan_save_stack+0x1c/0x40 [ 86.051955] __kasan_kmalloc+0x84/0xa0 [ 86.051955] mctp_rtm_newaddr+0x242/0x610 [ 86.051955] rtnetlink_rcv_msg+0x2fd/0x8b0 [ 86.051955] netlink_rcv_skb+0x11c/0x340 [ 86.051955] netlink_unicast+0x439/0x630 [ 86.051955] netlink_sendmsg+0x752/0xc00 [ 86.051955] sock_sendmsg+0xdd/0x110 [ 86.051955] __sys_sendto+0x1cc/0x2a0 [ 86.051955] __x64_sys_sendto+0xd8/0x1b0 [ 86.051955] do_syscall_64+0x3a/0x80 [ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 86.051955] [ 86.051955] Freed by task 301: [ 86.051955] kasan_save_stack+0x1c/0x40 [ 86.051955] kasan_set_track+0x21/0x30 [ 86.051955] kasan_set_free_info+0x20/0x30 [ 86.051955] __kasan_slab_free+0x104/0x170 [ 86.051955] kfree+0x8c/0x290 [ 86.051955] mctp_dev_notify+0x161/0x2c0 [ 86.051955] raw_notifier_call_chain+0x8b/0xc0 [ 86.051955] unregister_netdevice_many+0x299/0x1180 [ 86.051955] unregister_netdevice_queue+0x210/0x2f0 [ 86.051955] unregister_netdev+0x13/0x20 [ 86.051955] mctp_serial_close+0x6d/0xa0 [ 86.051955] tty_ldisc_kill+0x31/0xa0 [ 86.051955] tty_ldisc_hangup+0x24f/0x560 [ 86.051955] __tty_hangup.part.28+0x2ce/0x6b0 [ 86.051955] tty_release+0x327/0xc70 [ 86.051955] __fput+0x1df/0x8b0 [ 86.051955] task_work_run+0xca/0x150 [ 86.051955] exit_to_user_mode_prepare+0x114/0x120 [ 86.051955] syscall_exit_to_user_mode+0x12/0x20 [ 86.051955] do_syscall_64+0x46/0x80 [ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 86.051955] [ 86.051955] The buggy address belongs to the object at ffff888005f298c0 [ 86.051955] which belongs to the cache kmalloc-8 of size 8 [ 86.051955] The buggy address is located 0 bytes inside of [ 86.051955] 8-byte region [ffff888005f298c0, ffff888005f298c8) [ 86.051955] [ 86.051955] The buggy address belongs to the physical page: [ 86.051955] flags: 0x100000000000200(slab|node=0|zone=1) [ 86.051955] raw: 0100000000000200 dead000000000100 dead000000000122 ffff888005c42280 [ 86.051955] raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000 [ 86.051955] page dumped because: kasan: bad access detected [ 86.051955] [ 86.051955] Memory state around the buggy address: [ 86.051955] ffff888005f29780: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 [ 86.051955] ffff888005f29800: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc [ 86.051955] >ffff888005f29880: fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc [ 86.051955] ^ [ 86.051955] ffff888005f29900: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc [ 86.051955] ffff888005f29980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc [ 86.051955] ================================================================== To this end, just like the commit e04480920d1e ("Bluetooth: defer cleanup of resources in hci_unregister_dev()") this patch defers the destructive kfree(mdev->addrs) in mctp_unregister to the mctp_dev_put, where the refcount of mdev is zero and the entire device is reclaimed. This prevents the use-after-free because the sendmsg thread holds the reference of mdev in the mctp_route object. Fixes: 583be982d934 (mctp: Add device handling and netlink interface) Signed-off-by: Lin Ma Acked-by: Jeremy Kerr Link: https://lore.kernel.org/r/20220422114340.32346-1-linma@zju.edu.cn Signed-off-by: Paolo Abeni

mctp: Use output netdev to allocate skb headroom

2022-04-01T11:04:15+00:00

Previously the skb was allocated with headroom MCTP_HEADER_MAXLEN, but that isn't sufficient if we are using devs that are not MCTP specific. This also adds a check that the smctp_halen provided to sendmsg for extended addressing is the correct size for the netdev. Fixes: 833ef3b91de6 ("mctp: Populate socket implementation") Reported-by: Matthew Rinaldi Signed-off-by: Matt Johnston Signed-off-by: David S. Miller

mctp: Fix check for dev_hard_header() result

2022-04-01T11:04:15+00:00

dev_hard_header() returns the length of the header, so we need to test for negative errors rather than non-zero. Fixes: 889b7da23abf ("mctp: Add initial routing framework") Signed-off-by: Matt Johnston Signed-off-by: David S. Miller

mctp: Avoid warning if unregister notifies twice

2022-02-26T06:23:23+00:00

Previously if an unregister notify handler ran twice (waiting for netdev to be released) it would print a warning in mctp_unregister() every subsequent time the unregister notify occured. Instead we only need to worry about the case where a mctp_ptr is set on an unknown device type. Signed-off-by: Matt Johnston Signed-off-by: Jakub Kicinski

mctp: Fix warnings reported by clang-analyzer

2022-02-23T12:31:39+00:00

net/mctp/device.c:140:11: warning: Assigned value is garbage or undefined [clang-analyzer-core.uninitialized.Assign] mcb->idx = idx; - Not a real problem due to how the callback runs, fix the warning. net/mctp/route.c:458:4: warning: Value stored to 'msk' is never read [clang-analyzer-deadcode.DeadStores] msk = container_of(key->sk, struct mctp_sock, sk); - 'msk' dead assignment can be removed here. Signed-off-by: Matt Johnston Signed-off-by: David S. Miller

mctp: Fix incorrect netdev unref for extended addr

2022-02-23T12:29:15+00:00

In the extended addressing local route output codepath dev_get_by_index_rcu() doesn't take a dev_hold() so we shouldn't dev_put(). Signed-off-by: Matt Johnston Signed-off-by: David S. Miller

mctp: make __mctp_dev_get() take a refcount hold

2022-02-23T12:29:15+00:00

Previously there was a race that could allow the mctp_dev refcount to hit zero: rcu_read_lock(); mdev = __mctp_dev_get(dev); // mctp_unregister() happens here, mdev->refs hits zero mctp_dev_hold(dev); rcu_read_unlock(); Now we make __mctp_dev_get() take the hold itself. It is safe to test against the zero refcount because __mctp_dev_get() is called holding rcu_read_lock and mctp_dev uses kfree_rcu(). Reported-by: Jakub Kicinski Signed-off-by: Matt Johnston Signed-off-by: David S. Miller

mctp: add address validity checking for packet receive

2022-02-19T05:24:29+00:00

This change adds some basic sanity checks for the source and dest headers of packets on initial receive. Signed-off-by: Jeremy Kerr Signed-off-by: Jakub Kicinski

mctp: replace mctp_address_ok with more fine-grained helpers

2022-02-19T05:24:28+00:00

Currently, we have mctp_address_ok(), which checks if an EID is in the "valid" range of 8-254 inclusive. However, 0 and 255 may also be valid addresses, depending on context. 0 is the NULL EID, which may be set when physical addressing is used. 255 is valid as a destination address for broadcasts. This change renames mctp_address_ok to mctp_address_unicast, and adds similar helpers for broadcast and null EIDs, which will be used in an upcoming commit. Signed-off-by: Jeremy Kerr Signed-off-by: Jakub Kicinski