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Eric Dumazet 176dd41e8c ppp: do not assume bh is held in ppp_channel_bridge_input() 
[ Upstream commit aec7291003 ]

Networking receive path is usually handled from BH handler.
However, some protocols need to acquire the socket lock, and
packets might be stored in the socket backlog is the socket was
owned by a user process.

In this case, release_sock(), __release_sock(), and sk_backlog_rcv()
might call the sk->sk_backlog_rcv() handler in process context.

sybot caught ppp was not considering this case in
ppp_channel_bridge_input() :

WARNING: inconsistent lock state
6.11.0-rc7-syzkaller-g5f5673607153 #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/1/24 [HC0[0]:SC1[1]:HE1:SE0] takes:
 ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
 ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
{SOFTIRQ-ON-W} state was registered at:
   lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5759
   __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
   _raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154
   spin_lock include/linux/spinlock.h:351 [inline]
   ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
   ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
   pppoe_rcv_core+0xfc/0x314 drivers/net/ppp/pppoe.c:379
   sk_backlog_rcv include/net/sock.h:1111 [inline]
   __release_sock+0x1a8/0x3d8 net/core/sock.c:3004
   release_sock+0x68/0x1b8 net/core/sock.c:3558
   pppoe_sendmsg+0xc8/0x5d8 drivers/net/ppp/pppoe.c:903
   sock_sendmsg_nosec net/socket.c:730 [inline]
   __sock_sendmsg net/socket.c:745 [inline]
   __sys_sendto+0x374/0x4f4 net/socket.c:2204
   __do_sys_sendto net/socket.c:2216 [inline]
   __se_sys_sendto net/socket.c:2212 [inline]
   __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2212
   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
   invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
   el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
   do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
   el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
   el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
   el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
irq event stamp: 282914
 hardirqs last  enabled at (282914): [<ffff80008b42e30c>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
 hardirqs last  enabled at (282914): [<ffff80008b42e30c>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
 hardirqs last disabled at (282913): [<ffff80008b42e13c>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
 hardirqs last disabled at (282913): [<ffff80008b42e13c>] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:162
 softirqs last  enabled at (282904): [<ffff8000801f8e88>] softirq_handle_end kernel/softirq.c:400 [inline]
 softirqs last  enabled at (282904): [<ffff8000801f8e88>] handle_softirqs+0xa3c/0xbfc kernel/softirq.c:582
 softirqs last disabled at (282909): [<ffff8000801fbdf8>] run_ksoftirqd+0x70/0x158 kernel/softirq.c:928

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&pch->downl);
  <Interrupt>
    lock(&pch->downl);

 *** DEADLOCK ***

1 lock held by ksoftirqd/1/24:
  #0: ffff80008f74dfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:325

stack backtrace:
CPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.11.0-rc7-syzkaller-g5f5673607153 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call trace:
  dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319
  show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326
  __dump_stack lib/dump_stack.c:93 [inline]
  dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:119
  dump_stack+0x1c/0x28 lib/dump_stack.c:128
  print_usage_bug+0x698/0x9ac kernel/locking/lockdep.c:4000
 mark_lock_irq+0x980/0xd2c
  mark_lock+0x258/0x360 kernel/locking/lockdep.c:4677
  __lock_acquire+0xf48/0x779c kernel/locking/lockdep.c:5096
  lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5759
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:351 [inline]
  ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
  ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
  ppp_async_process+0x98/0x150 drivers/net/ppp/ppp_async.c:495
  tasklet_action_common+0x318/0x3f4 kernel/softirq.c:785
  tasklet_action+0x68/0x8c kernel/softirq.c:811
  handle_softirqs+0x2e4/0xbfc kernel/softirq.c:554
  run_ksoftirqd+0x70/0x158 kernel/softirq.c:928
  smpboot_thread_fn+0x4b0/0x90c kernel/smpboot.c:164
  kthread+0x288/0x310 kernel/kthread.c:389
  ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

Fixes: 4cf476ced4 ("ppp: add PPPIOCBRIDGECHAN and PPPIOCUNBRIDGECHAN ioctls")
Reported-by: syzbot+bd8d55ee2acd0a71d8ce@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/66f661e2.050a0220.38ace9.000f.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Parkin <tparkin@katalix.com>
Cc: James Chapman <jchapman@katalix.com>
Link: https://patch.msgid.link/20240927074553.341910-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-10-17 15:11:21 +02:00
arch x86/entry: Remove unwanted instrumentation in common_interrupt() 2024-10-17 15:11:18 +02:00
block block: fix potential invalid pointer dereference in blk_add_partition 2024-10-17 15:10:48 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: xor - fix template benchmarking 2024-10-17 15:10:42 +02:00
Documentation f2fs: introduce F2FS_IPU_HONOR_OPU_WRITE ipu policy 2024-10-17 15:11:05 +02:00
drivers ppp: do not assume bh is held in ppp_channel_bridge_input() 2024-10-17 15:11:21 +02:00
fs ceph: remove the incorrect Fw reference check when dirtying pages 2024-10-17 15:11:19 +02:00
include netfilter: uapi: NFTA_FLOWTABLE_HOOK is NLA_NESTED 2024-10-17 15:11:20 +02:00
init init/main.c: Fix potential static_command_line memory overflow 2024-04-27 17:05:28 +02:00
io_uring io_uring/io-wq: limit retrying worker initialisation 2024-08-19 05:45:22 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel static_call: Replace pointless WARN_ON() in static_call_module_notify() 2024-10-17 15:11:19 +02:00
lib debugobjects: Fix conditions in fill_pool() 2024-10-17 15:11:14 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: only enforce minimum stack gap size if it's sensible 2024-10-17 15:11:18 +02:00
net ipv4: ip_gre: Fix drops of small packets in ipgre_xmit 2024-10-17 15:11:21 +02:00
samples Add gitignore file for samples/fanotify/ subdirectory 2024-07-27 10:46:16 +02:00
scripts scripts: kconfig: merge_config: config files: add a trailing newline 2024-10-17 15:10:33 +02:00
security bpf: lsm: Set bpf_lsm_blob_sizes.lbs_task to 0 2024-10-17 15:11:18 +02:00
sound ASoC: rt5682: Return devm_of_clk_add_hw_provider to transfer the error 2024-10-17 15:11:10 +02:00
tools perf time-utils: Fix 32-bit nsec parsing 2024-10-17 15:10:59 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-10 16:18:34 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS trace: Relocate event helper files 2024-04-10 16:19:24 +02:00
Makefile Linux 5.15.167 2024-09-12 11:07:53 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.