7b50ee3dad
In the function node_lost_contact(), we call __skb_queue_purge() without
grabbing the list->lock. This can cause to a race-condition why processing
the list 'namedq' in calling path tipc_named_rcv()->tipc_named_dequeue().
[] BUG: kernel NULL pointer dereference, address: 0000000000000000
[] #PF: supervisor read access in kernel mode
[] #PF: error_code(0x0000) - not-present page
[] PGD 7ca63067 P4D 7ca63067 PUD 6c553067 PMD 0
[] Oops: 0000 [#1] SMP NOPTI
[] CPU: 1 PID: 15 Comm: ksoftirqd/1 Tainted: G O 5.9.0-rc6+ #2
[] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS [...]
[] RIP: 0010:tipc_named_rcv+0x103/0x320 [tipc]
[] Code: 41 89 44 24 10 49 8b 16 49 8b 46 08 49 c7 06 00 00 00 [...]
[] RSP: 0018:ffffc900000a7c58 EFLAGS: 00000282
[] RAX: 00000000000012ec RBX: 0000000000000000 RCX: ffff88807bde1270
[] RDX: 0000000000002c7c RSI: 0000000000002c7c RDI: ffff88807b38f1a8
[] RBP: ffff88807b006288 R08: ffff88806a367800 R09: ffff88806a367900
[] R10: ffff88806a367a00 R11: ffff88806a367b00 R12: ffff88807b006258
[] R13: ffff88807b00628a R14: ffff888069334d00 R15: ffff88806a434600
[] FS: 0000000000000000(0000) GS:ffff888079480000(0000) knlGS:0[...]
[] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[] CR2: 0000000000000000 CR3: 0000000077320000 CR4: 00000000000006e0
[] Call Trace:
[] ? tipc_bcast_rcv+0x9a/0x1a0 [tipc]
[] tipc_rcv+0x40d/0x670 [tipc]
[] ? _raw_spin_unlock+0xa/0x20
[] tipc_l2_rcv_msg+0x55/0x80 [tipc]
[] __netif_receive_skb_one_core+0x8c/0xa0
[] process_backlog+0x98/0x140
[] net_rx_action+0x13a/0x420
[] __do_softirq+0xdb/0x316
[] ? smpboot_thread_fn+0x2f/0x1e0
[] ? smpboot_thread_fn+0x74/0x1e0
[] ? smpboot_thread_fn+0x14e/0x1e0
[] run_ksoftirqd+0x1a/0x40
[] smpboot_thread_fn+0x149/0x1e0
[] ? sort_range+0x20/0x20
[] kthread+0x131/0x150
[] ? kthread_unuse_mm+0xa0/0xa0
[] ret_from_fork+0x22/0x30
[] Modules linked in: veth tipc(O) ip6_udp_tunnel udp_tunnel [...]
[] CR2: 0000000000000000
[] ---[ end trace 65c276a8e2e2f310 ]---
To fix this, we need to grab the lock of the 'namedq' list on both
path calling.
Fixes: cad2929dc432 ("tipc: update a binding service via broadcast")
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Hoang Huu Le <hoang.h.le@dektech.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.