linux/kernel/bpf
David Howells fc4aaf9fb3 net: Fix suspicious RCU usage in bpf_sk_reuseport_detach()
bpf_sk_reuseport_detach() calls __rcu_dereference_sk_user_data_with_flags()
to obtain the value of sk->sk_user_data, but that function is only usable
if the RCU read lock is held, and neither that function nor any of its
callers hold it.

Fix this by adding a new helper, __locked_read_sk_user_data_with_flags()
that checks to see if sk->sk_callback_lock() is held and use that here
instead.

Alternatively, making __rcu_dereference_sk_user_data_with_flags() use
rcu_dereference_checked() might suffice.

Without this, the following warning can be occasionally observed:

=============================
WARNING: suspicious RCU usage
6.0.0-rc1-build2+ #563 Not tainted
-----------------------------
include/net/sock.h:592 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
5 locks held by locktest/29873:
 #0: ffff88812734b550 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: __sock_release+0x77/0x121
 #1: ffff88812f5621b0 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_close+0x1c/0x70
 #2: ffff88810312f5c8 (&h->lhash2[i].lock){+.+.}-{2:2}, at: inet_unhash+0x76/0x1c0
 #3: ffffffff83768bb8 (reuseport_lock){+...}-{2:2}, at: reuseport_detach_sock+0x18/0xdd
 #4: ffff88812f562438 (clock-AF_INET){++..}-{2:2}, at: bpf_sk_reuseport_detach+0x24/0xa4

stack backtrace:
CPU: 1 PID: 29873 Comm: locktest Not tainted 6.0.0-rc1-build2+ #563
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x4c/0x5f
 bpf_sk_reuseport_detach+0x6d/0xa4
 reuseport_detach_sock+0x75/0xdd
 inet_unhash+0xa5/0x1c0
 tcp_set_state+0x169/0x20f
 ? lockdep_sock_is_held+0x3a/0x3a
 ? __lock_release.isra.0+0x13e/0x220
 ? reacquire_held_locks+0x1bb/0x1bb
 ? hlock_class+0x31/0x96
 ? mark_lock+0x9e/0x1af
 __tcp_close+0x50/0x4b6
 tcp_close+0x28/0x70
 inet_release+0x8e/0xa7
 __sock_release+0x95/0x121
 sock_close+0x14/0x17
 __fput+0x20f/0x36a
 task_work_run+0xa3/0xcc
 exit_to_user_mode_prepare+0x9c/0x14d
 syscall_exit_to_user_mode+0x18/0x44
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: cf8c1e9672 ("net: refactor bpf_sk_reuseport_detach()")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hawkins Jiawei <yin31149@gmail.com>
Link: https://lore.kernel.org/r/166064248071.3502205.10036394558814861778.stgit@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-17 16:42:59 -07:00
..
preload bpf: iterators: Build and use lightweight bootstrap version of bpftool 2022-07-15 12:01:30 -07:00
arraymap.c bpf: Acquire map uref in .init_seq_private for array map iterator 2022-08-10 10:12:47 -07:00
bloom_filter.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
bpf_inode_storage.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
bpf_iter.c bpf: Only allow sleepable program for resched-able iterator 2022-08-10 10:12:48 -07:00
bpf_local_storage.c bpf: Fix usage of trace RCU in local storage. 2022-04-19 17:55:45 -07:00
bpf_lru_list.c bpf_lru_list: Read double-checked variable once without lock 2021-02-10 15:54:26 -08:00
bpf_lru_list.h printk: stop including cache.h from printk.h 2022-05-13 07:20:07 -07:00
bpf_lsm.c bpf: fix lsm_cgroup build errors on esoteric configs 2022-07-19 09:40:41 -07:00
bpf_struct_ops_types.h bpf: Add dummy BPF STRUCT_OPS for test purpose 2021-11-01 14:10:00 -07:00
bpf_struct_ops.c bpf: Remove is_valid_bpf_tramp_flags() 2022-07-11 21:04:58 +02:00
bpf_task_storage.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
btf.c bpf: btf: Fix vsnprintf return value check 2022-07-29 09:57:14 -07:00
cgroup.c bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP 2022-06-29 13:21:52 -07:00
core.c Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-07-22 16:55:44 -07:00
cpumap.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
devmap.c bpf, devmap: Compute proper xdp_frame len redirecting frames 2022-07-26 16:26:19 +02:00
disasm.c bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause 2021-09-02 14:49:23 +02:00
disasm.h bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause 2021-09-02 14:49:23 +02:00
dispatcher.c
hashtab.c bpf: Acquire map uref in .init_seq_private for hash map iterator 2022-08-10 10:12:47 -07:00
helpers.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-07-14 15:27:35 -07:00
inode.c bpf: Convert bpf_preload.ko to use light skeleton. 2022-02-10 23:31:51 +01:00
Kconfig rcu: Make the TASKS_RCU Kconfig option be selected 2022-04-20 16:52:58 -07:00
link_iter.c bpf: Add bpf_link iterator 2022-05-10 11:20:45 -07:00
local_storage.c bpf: Make non-preallocated allocation low priority 2022-07-12 17:44:27 -07:00
lpm_trie.c bpf: Make non-preallocated allocation low priority 2022-07-12 17:44:27 -07:00
Makefile bpf: Add bpf_link iterator 2022-05-10 11:20:45 -07:00
map_in_map.c bpf: Allow storing unreferenced kptr in map 2022-04-25 17:31:35 -07:00
map_in_map.h bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
map_iter.c bpf: Introduce MEM_RDONLY flag 2021-12-18 13:27:41 -08:00
mmap_unlock_work.h bpf: Introduce helper bpf_find_vma 2021-11-07 11:54:51 -08:00
net_namespace.c net: Add includes masked by netdevice.h including uapi/bpf.h 2021-12-29 20:03:05 -08:00
offload.c
percpu_freelist.c bpf: avoid grabbing spin_locks of all cpus when no free elems 2022-06-11 14:25:35 -07:00
percpu_freelist.h bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
prog_iter.c bpf: Refactor bpf_iter_reg to have separate seq_info member 2020-07-25 20:16:32 -07:00
queue_stack_maps.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
reuseport_array.c net: Fix suspicious RCU usage in bpf_sk_reuseport_detach() 2022-08-17 16:42:59 -07:00
ringbuf.c bpf: Dynptr support for ring buffers 2022-05-23 14:31:28 -07:00
stackmap.c bpf: Compute map_btf_id during build time 2022-04-26 11:35:21 -07:00
syscall.c bpf: Shut up kern_sys_bpf warning. 2022-08-10 23:58:13 -07:00
sysfs_btf.c bpf: Load and verify kernel module BTFs 2020-11-10 15:25:53 -08:00
task_iter.c bpf: Remove redundant assignment to meta.seq in __task_seq_show() 2022-04-11 21:14:34 +02:00
tnum.c bpf, tnums: Provably sound, faster, and more precise algorithm for tnum_mul 2021-06-01 13:34:15 +02:00
trampoline.c bpf: Cleanup ftrace hash in bpf_trampoline_put 2022-08-05 09:43:58 -07:00
verifier.c bpf: Switch to new kfunc flags infrastructure 2022-07-21 20:59:42 -07:00