…s_lock

For storing a value to a queue attribute, the queue_attr_store function
first freezes the queue (->q_usage_counter(io)) and then acquire
->sysfs_lock. This seems not correct as the usual ordering should be to
acquire ->sysfs_lock before freezing the queue. This incorrect ordering
causes the following lockdep splat which we are able to reproduce always
simply by accessing /sys/kernel/debug file using ls command:

[   57.597146] WARNING: possible circular locking dependency detected
[   57.597154] 6.12.0-10553-gb86545e02e8c #20 Tainted: G        W
[   57.597162] ------------------------------------------------------
[   57.597168] ls/4605 is trying to acquire lock:
[   57.597176] c00000003eb56710 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x58/0xc0
[   57.597200]
               but task is already holding lock:
[   57.597207] c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4
[   57.597226]
               which lock already depends on the new lock.

[   57.597233]
               the existing dependency chain (in reverse order) is:
[   57.597241]
               -> #5 (&sb->s_type->i_mutex_key#3){++++}-{4:4}:
[   57.597255]        down_write+0x6c/0x18c
[   57.597264]        start_creating+0xb4/0x24c
[   57.597274]        debugfs_create_dir+0x2c/0x1e8
[   57.597283]        blk_register_queue+0xec/0x294
[   57.597292]        add_disk_fwnode+0x2e4/0x548
[   57.597302]        brd_alloc+0x2c8/0x338
[   57.597309]        brd_init+0x100/0x178
[   57.597317]        do_one_initcall+0x88/0x3e4
[   57.597326]        kernel_init_freeable+0x3cc/0x6e0
[   57.597334]        kernel_init+0x34/0x1cc
[   57.597342]        ret_from_kernel_user_thread+0x14/0x1c
[   57.597350]
               -> #4 (&q->debugfs_mutex){+.+.}-{4:4}:
[   57.597362]        __mutex_lock+0xfc/0x12a0
[   57.597370]        blk_register_queue+0xd4/0x294
[   57.597379]        add_disk_fwnode+0x2e4/0x548
[   57.597388]        brd_alloc+0x2c8/0x338
[   57.597395]        brd_init+0x100/0x178
[   57.597402]        do_one_initcall+0x88/0x3e4
[   57.597410]        kernel_init_freeable+0x3cc/0x6e0
[   57.597418]        kernel_init+0x34/0x1cc
[   57.597426]        ret_from_kernel_user_thread+0x14/0x1c
[   57.597434]
               -> #3 (&q->sysfs_lock){+.+.}-{4:4}:
[   57.597446]        __mutex_lock+0xfc/0x12a0
[   57.597454]        queue_attr_store+0x9c/0x110
[   57.597462]        sysfs_kf_write+0x70/0xb0
[   57.597471]        kernfs_fop_write_iter+0x1b0/0x2ac
[   57.597480]        vfs_write+0x3dc/0x6e8
[   57.597488]        ksys_write+0x84/0x140
[   57.597495]        system_call_exception+0x130/0x360
[   57.597504]        system_call_common+0x160/0x2c4
[   57.597516]
               -> #2 (&q->q_usage_counter(io)#21){++++}-{0:0}:
[   57.597530]        __submit_bio+0x5ec/0x828
[   57.597538]        submit_bio_noacct_nocheck+0x1e4/0x4f0
[   57.597547]        iomap_readahead+0x2a0/0x448
[   57.597556]        xfs_vm_readahead+0x28/0x3c
[   57.597564]        read_pages+0x88/0x41c
[   57.597571]        page_cache_ra_unbounded+0x1ac/0x2d8
[   57.597580]        filemap_get_pages+0x188/0x984
[   57.597588]        filemap_read+0x13c/0x4bc
[   57.597596]        xfs_file_buffered_read+0x88/0x17c
[   57.597605]        xfs_file_read_iter+0xac/0x158
[   57.597614]        vfs_read+0x2d4/0x3b4
[   57.597622]        ksys_read+0x84/0x144
[   57.597629]        system_call_exception+0x130/0x360
[   57.597637]        system_call_common+0x160/0x2c4
[   57.597647]
               -> #1 (mapping.invalidate_lock#2){++++}-{4:4}:
[   57.597661]        down_read+0x6c/0x220
[   57.597669]        filemap_fault+0x870/0x100c
[   57.597677]        xfs_filemap_fault+0xc4/0x18c
[   57.597684]        __do_fault+0x64/0x164
[   57.597693]        __handle_mm_fault+0x1274/0x1dac
[   57.597702]        handle_mm_fault+0x248/0x484
[   57.597711]        ___do_page_fault+0x428/0xc0c
[   57.597719]        hash__do_page_fault+0x30/0x68
[   57.597727]        do_hash_fault+0x90/0x35c
[   57.597736]        data_access_common_virt+0x210/0x220
[   57.597745]        _copy_from_user+0xf8/0x19c
[   57.597754]        sel_write_load+0x178/0xd54
[   57.597762]        vfs_write+0x108/0x6e8
[   57.597769]        ksys_write+0x84/0x140
[   57.597777]        system_call_exception+0x130/0x360
[   57.597785]        system_call_common+0x160/0x2c4
[   57.597794]
               -> #0 (&mm->mmap_lock){++++}-{4:4}:
[   57.597806]        __lock_acquire+0x17cc/0x2330
[   57.597814]        lock_acquire+0x138/0x400
[   57.597822]        __might_fault+0x7c/0xc0
[   57.597830]        filldir64+0xe8/0x390
[   57.597839]        dcache_readdir+0x80/0x2d4
[   57.597846]        iterate_dir+0xd8/0x1d4
[   57.597855]        sys_getdents64+0x88/0x2d4
[   57.597864]        system_call_exception+0x130/0x360
[   57.597872]        system_call_common+0x160/0x2c4
[   57.597881]
               other info that might help us debug this:

[   57.597888] Chain exists of:
                 &mm->mmap_lock --> &q->debugfs_mutex --> &sb->s_type->i_mutex_key#3

[   57.597905]  Possible unsafe locking scenario:

[   57.597911]        CPU0                    CPU1
[   57.597917]        ----                    ----
[   57.597922]   rlock(&sb->s_type->i_mutex_key#3);
[   57.597932]                                lock(&q->debugfs_mutex);
[   57.597940]                                lock(&sb->s_type->i_mutex_key#3);
[   57.597950]   rlock(&mm->mmap_lock);
[   57.597958]
                *** DEADLOCK ***

[   57.597965] 2 locks held by ls/4605:
[   57.597971]  #0: c0000000137c12f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0xcc/0x154
[   57.597989]  #1: c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4

Prevent the above lockdep warning by acquiring ->sysfs_lock before
freezing the queue while storing a queue attribute in queue_attr_store
function. Later, we also found[1] another function __blk_mq_update_nr_
hw_queues where we first freeze queue and then acquire the ->sysfs_lock.
So we've also updated lock ordering in __blk_mq_update_nr_hw_queues
function and ensured that in all code paths we follow the correct lock
ordering i.e. acquire ->sysfs_lock before freezing the queue.

[1] https://lore.kernel.org/all/CAFj5m9Ke8+EHKQBs_Nk6hqd=LGXtk4mUxZUN5==ZcCjnZSBwHw@mail.gmail.com/

Reported-by: [email protected]
Fixes: af28141 ("block: freeze the queue in queue_attr_store")
Tested-by: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Nilay Shroff <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

The following crash is observed while handling an IOMMU fault with a
recent kernel:

kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle page fault for address: ffff8c708299f700
PGD 19ee01067 P4D 19ee01067 PUD 101c10063 PMD 80000001028001e3
Oops: Oops: 0011 [#1] SMP NOPTI
CPU: 4 UID: 0 PID: 139 Comm: irq/25-AMD-Vi Not tainted 6.15.0-rc1+ #20 PREEMPT(lazy)
Hardware name: LENOVO 21D0/LNVNB161216, BIOS J6CN50WW 09/27/2024
RIP: 0010:0xffff8c708299f700
Call Trace:
 <TASK>
 ? report_iommu_fault+0x78/0xd3
 ? amd_iommu_report_page_fault+0x91/0x150
 ? amd_iommu_int_thread+0x77/0x180
 ? __pfx_irq_thread_fn+0x10/0x10
 ? irq_thread_fn+0x23/0x60
 ? irq_thread+0xf9/0x1e0
 ? __pfx_irq_thread_dtor+0x10/0x10
 ? __pfx_irq_thread+0x10/0x10
 ? kthread+0xfc/0x240
 ? __pfx_kthread+0x10/0x10
 ? ret_from_fork+0x34/0x50
 ? __pfx_kthread+0x10/0x10
 ? ret_from_fork_asm+0x1a/0x30
 </TASK>

report_iommu_fault() checks for an installed handler comparing the
corresponding field to NULL. It can (and could before) be called for a
domain with a different cookie type - IOMMU_COOKIE_DMA_IOVA, specifically.
Cookie is represented as a union so we may end up with a garbage value
treated there if this happens for a domain with another cookie type.

Formerly there were two exclusive cookie types in the union.
IOMMU_DOMAIN_SVA has a dedicated iommu_report_device_fault().

Call the fault handler only if the passed domain has a required cookie
type.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 6aa63a4 ("iommu: Sort out domain user data")
Signed-off-by: Fedor Pchelkin <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Mitigate e.g. the following:

    # echo 1e789080.lpc-snoop > /sys/bus/platform/drivers/aspeed-lpc-snoop/unbind
    ...
    [  120.363594] Unable to handle kernel NULL pointer dereference at virtual address 00000004 when write
    [  120.373866] [00000004] *pgd=00000000
    [  120.377910] Internal error: Oops: 805 [#1] SMP ARM
    [  120.383306] CPU: 1 UID: 0 PID: 315 Comm: sh Not tainted 6.15.0-rc1-00009-g926217bc7d7d-dirty #20 NONE
    ...
    [  120.679543] Call trace:
    [  120.679559]  misc_deregister from aspeed_lpc_snoop_remove+0x84/0xac
    [  120.692462]  aspeed_lpc_snoop_remove from platform_remove+0x28/0x38
    [  120.700996]  platform_remove from device_release_driver_internal+0x188/0x200
    ...

Fixes: 9f4f9ae ("drivers/misc: add Aspeed LPC snoop driver")
Cc: [email protected]
Cc: Jean Delvare <[email protected]>
Acked-by: Jean Delvare <[email protected]>
Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-2-3cdd59c934d3@codeconstruct.com.au
Signed-off-by: Andrew Jeffery <[email protected]>

page_pool_put_full_page() should only be invoked when freeing Rx buffers
or building a skb if the size is too short. At other times, the pages
need to be reused. So remove the redundant page put. In the original
code, double free pages cause kernel panic:

[  876.949834]  __irq_exit_rcu+0xc7/0x130
[  876.949836]  common_interrupt+0xb8/0xd0
[  876.949838]  </IRQ>
[  876.949838]  <TASK>
[  876.949840]  asm_common_interrupt+0x22/0x40
[  876.949841] RIP: 0010:cpuidle_enter_state+0xc2/0x420
[  876.949843] Code: 00 00 e8 d1 1d 5e ff e8 ac f0 ff ff 49 89 c5 0f 1f 44 00 00 31 ff e8 cd fc 5c ff 45 84 ff 0f 85 40 02 00 00 fb 0f 1f 44 00 00 <45> 85 f6 0f 88 84 01 00 00 49 63 d6 48 8d 04 52 48 8d 04 82 49 8d
[  876.949844] RSP: 0018:ffffaa7340267e78 EFLAGS: 00000246
[  876.949845] RAX: ffff9e3f135be000 RBX: 0000000000000002 RCX: 0000000000000000
[  876.949846] RDX: 000000cc2dc4cb7c RSI: ffffffff89ee49ae RDI: ffffffff89ef9f9e
[  876.949847] RBP: ffff9e378f940800 R08: 0000000000000002 R09: 00000000000000ed
[  876.949848] R10: 000000000000afc8 R11: ffff9e3e9e5a9b6c R12: ffffffff8a6d8580
[  876.949849] R13: 000000cc2dc4cb7c R14: 0000000000000002 R15: 0000000000000000
[  876.949852]  ? cpuidle_enter_state+0xb3/0x420
[  876.949855]  cpuidle_enter+0x29/0x40
[  876.949857]  cpuidle_idle_call+0xfd/0x170
[  876.949859]  do_idle+0x7a/0xc0
[  876.949861]  cpu_startup_entry+0x25/0x30
[  876.949862]  start_secondary+0x117/0x140
[  876.949864]  common_startup_64+0x13e/0x148
[  876.949867]  </TASK>
[  876.949868] ---[ end trace 0000000000000000 ]---
[  876.949869] ------------[ cut here ]------------
[  876.949870] list_del corruption, ffffead40445a348->next is NULL
[  876.949873] WARNING: CPU: 14 PID: 0 at lib/list_debug.c:52 __list_del_entry_valid_or_report+0x67/0x120
[  876.949875] Modules linked in: snd_hrtimer(E) bnep(E) binfmt_misc(E) amdgpu(E) squashfs(E) vfat(E) loop(E) fat(E) amd_atl(E) snd_hda_codec_realtek(E) intel_rapl_msr(E) snd_hda_codec_generic(E) intel_rapl_common(E) snd_hda_scodec_component(E) snd_hda_codec_hdmi(E) snd_hda_intel(E) edac_mce_amd(E) snd_intel_dspcfg(E) snd_hda_codec(E) snd_hda_core(E) amdxcp(E) kvm_amd(E) snd_hwdep(E) gpu_sched(E) drm_panel_backlight_quirks(E) cec(E) snd_pcm(E) drm_buddy(E) snd_seq_dummy(E) drm_ttm_helper(E) btusb(E) kvm(E) snd_seq_oss(E) btrtl(E) ttm(E) btintel(E) snd_seq_midi(E) btbcm(E) drm_exec(E) snd_seq_midi_event(E) i2c_algo_bit(E) snd_rawmidi(E) bluetooth(E) drm_suballoc_helper(E) irqbypass(E) snd_seq(E) ghash_clmulni_intel(E) sha512_ssse3(E) drm_display_helper(E) aesni_intel(E) snd_seq_device(E) rfkill(E) snd_timer(E) gf128mul(E) drm_client_lib(E) drm_kms_helper(E) snd(E) i2c_piix4(E) joydev(E) soundcore(E) wmi_bmof(E) ccp(E) k10temp(E) i2c_smbus(E) gpio_amdpt(E) i2c_designware_platform(E) gpio_generic(E) sg(E)
[  876.949914]  i2c_designware_core(E) sch_fq_codel(E) parport_pc(E) drm(E) ppdev(E) lp(E) parport(E) fuse(E) nfnetlink(E) ip_tables(E) ext4 crc16 mbcache jbd2 sd_mod sfp mdio_i2c i2c_core txgbe ahci ngbe pcs_xpcs libahci libwx r8169 phylink libata realtek ptp pps_core video wmi
[  876.949933] CPU: 14 UID: 0 PID: 0 Comm: swapper/14 Kdump: loaded Tainted: G        W   E       6.16.0-rc2+ #20 PREEMPT(voluntary)
[  876.949935] Tainted: [W]=WARN, [E]=UNSIGNED_MODULE
[  876.949936] Hardware name: Micro-Star International Co., Ltd. MS-7E16/X670E GAMING PLUS WIFI (MS-7E16), BIOS 1.90 12/31/2024
[  876.949936] RIP: 0010:__list_del_entry_valid_or_report+0x67/0x120
[  876.949938] Code: 00 00 00 48 39 7d 08 0f 85 a6 00 00 00 5b b8 01 00 00 00 5d 41 5c e9 73 0d 93 ff 48 89 fe 48 c7 c7 a0 31 e8 89 e8 59 7c b3 ff <0f> 0b 31 c0 5b 5d 41 5c e9 57 0d 93 ff 48 89 fe 48 c7 c7 c8 31 e8
[  876.949940] RSP: 0018:ffffaa73405d0c60 EFLAGS: 00010282
[  876.949941] RAX: 0000000000000000 RBX: ffffead40445a348 RCX: 0000000000000000
[  876.949942] RDX: 0000000000000105 RSI: 0000000000000001 RDI: 00000000ffffffff
[  876.949943] RBP: 0000000000000000 R08: 000000010006dfde R09: ffffffff8a47d150
[  876.949944] R10: ffffffff8a47d150 R11: 0000000000000003 R12: dead000000000122
[  876.949945] R13: ffff9e3e9e5af700 R14: ffffead40445a348 R15: ffff9e3e9e5af720
[  876.949946] FS:  0000000000000000(0000) GS:ffff9e3f135be000(0000) knlGS:0000000000000000
[  876.949947] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  876.949948] CR2: 00007fa58b480048 CR3: 0000000156724000 CR4: 0000000000750ef0
[  876.949949] PKRU: 55555554
[  876.949950] Call Trace:
[  876.949951]  <IRQ>
[  876.949952]  __rmqueue_pcplist+0x53/0x2c0
[  876.949955]  alloc_pages_bulk_noprof+0x2e0/0x660
[  876.949958]  __page_pool_alloc_pages_slow+0xa9/0x400
[  876.949961]  page_pool_alloc_pages+0xa/0x20
[  876.949963]  wx_alloc_rx_buffers+0xd7/0x110 [libwx]
[  876.949967]  wx_clean_rx_irq+0x262/0x430 [libwx]
[  876.949971]  wx_poll+0x92/0x130 [libwx]
[  876.949975]  __napi_poll+0x28/0x190
[  876.949977]  net_rx_action+0x301/0x3f0
[  876.949980]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949981]  ? profile_tick+0x30/0x70
[  876.949983]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949984]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949986]  ? timerqueue_add+0xa3/0xc0
[  876.949988]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949989]  ? __raise_softirq_irqoff+0x16/0x70
[  876.949991]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949993]  ? srso_alias_return_thunk+0x5/0xfbef5
[  876.949994]  ? wx_msix_clean_rings+0x41/0x50 [libwx]
[  876.949998]  handle_softirqs+0xf9/0x2c0

Fixes: 3c47e8a ("net: libwx: Support to receive packets in NAPI")
Cc: [email protected]
Signed-off-by: Jiawen Wu <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Syzkaller reported the following splat:

  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]
  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]
  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline]
  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153
  Modules linked in:
  CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary)
  Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
  RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]
  RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]
  RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline]
  RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153
  Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 <0f> 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00
  RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45
  RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001
  RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
  R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000
  FS:  00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0
  Call Trace:
   <IRQ>
   tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432
   tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975
   tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166
   tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925
   tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363
   ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205
   ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233
   NF_HOOK include/linux/netfilter.h:317 [inline]
   NF_HOOK include/linux/netfilter.h:311 [inline]
   ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254
   dst_input include/net/dst.h:469 [inline]
   ip_rcv_finish net/ipv4/ip_input.c:447 [inline]
   NF_HOOK include/linux/netfilter.h:317 [inline]
   NF_HOOK include/linux/netfilter.h:311 [inline]
   ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567
   __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975
   __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088
   process_backlog+0x301/0x1360 net/core/dev.c:6440
   __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453
   napi_poll net/core/dev.c:7517 [inline]
   net_rx_action+0xb44/0x1010 net/core/dev.c:7644
   handle_softirqs+0x1d0/0x770 kernel/softirq.c:579
   do_softirq+0x3f/0x90 kernel/softirq.c:480
   </IRQ>
   <TASK>
   __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407
   local_bh_enable include/linux/bottom_half.h:33 [inline]
   inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524
   mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985
   mptcp_check_listen_stop net/mptcp/mib.h:118 [inline]
   __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000
   mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066
   inet_release+0xed/0x200 net/ipv4/af_inet.c:435
   inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487
   __sock_release+0xb3/0x270 net/socket.c:649
   sock_close+0x1c/0x30 net/socket.c:1439
   __fput+0x402/0xb70 fs/file_table.c:465
   task_work_run+0x150/0x240 kernel/task_work.c:227
   resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
   exit_to_user_mode_loop+0xd4/0xe0 kernel/entry/common.c:114
   exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
   syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
   syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
   do_syscall_64+0x245/0x360 arch/x86/entry/syscall_64.c:100
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x7fc92f8a36ad
  Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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:00007ffcf52802d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
  RAX: 0000000000000000 RBX: 00007ffcf52803a8 RCX: 00007fc92f8a36ad
  RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
  RBP: 00007fc92fae7ba0 R08: 0000000000000001 R09: 0000002800000000
  R10: 00007fc92f700000 R11: 0000000000000246 R12: 00007fc92fae5fac
  R13: 00007fc92fae5fa0 R14: 0000000000026d00 R15: 0000000000026c51
   </TASK>
  irq event stamp: 4068
  hardirqs last  enabled at (4076): [<ffffffff81544816>] __up_console_sem+0x76/0x80 kernel/printk/printk.c:344
  hardirqs last disabled at (4085): [<ffffffff815447fb>] __up_console_sem+0x5b/0x80 kernel/printk/printk.c:342
  softirqs last  enabled at (3096): [<ffffffff840e1be0>] local_bh_enable include/linux/bottom_half.h:33 [inline]
  softirqs last  enabled at (3096): [<ffffffff840e1be0>] inet_csk_listen_stop+0x2c0/0x1070 net/ipv4/inet_connection_sock.c:1524
  softirqs last disabled at (3097): [<ffffffff813b6b9f>] do_softirq+0x3f/0x90 kernel/softirq.c:480

Since we need to track the 'fallback is possible' condition and the
fallback status separately, there are a few possible races open between
the check and the actual fallback action.

Add a spinlock to protect the fallback related information and use it
close all the possible related races. While at it also remove the
too-early clearing of allow_infinite_fallback in __mptcp_subflow_connect():
the field will be correctly cleared by subflow_finish_connect() if/when
the connection will complete successfully.

If fallback is not possible, as per RFC, reset the current subflow.

Since the fallback operation can now fail and return value should be
checked, rename the helper accordingly.

Fixes: 0530020 ("mptcp: track and update contiguous data status")
Cc: [email protected]
Reported-by: Matthieu Baerts <[email protected]>
Closes: multipath-tcp/mptcp_net-next#570
Reported-by: [email protected]
Closes: multipath-tcp/mptcp_net-next#555
Signed-off-by: Paolo Abeni <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>