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block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()#22

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block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()#22
blktests-ci[bot] wants to merge 12 commits intofor-next_basefrom
series/980640=>for-next

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@blktests-ci blktests-ci Bot commented Jul 10, 2025

Pull request for series with
subject: block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=980640

axboe and others added 12 commits July 7, 2025 19:42
* io_uring-6.16:
  io_uring/zcrx: fix pp destruction warnings
* block-6.16:
  block: reject bs > ps block devices when THP is disabled
  nbd: fix uaf in nbd_genl_connect() error path
  md/md-bitmap: fix GPF in bitmap_get_stats()
  md/raid1,raid10: strip REQ_NOWAIT from member bios
  raid10: cleanup memleak at raid10_make_request
  md/raid1: Fix stack memory use after return in raid1_reshape
* for-6.17/io_uring:
  io_uring/rw: cast rw->flags assignment to rwf_t
  io_uring: don't use int for ABI
  io_uring/rsrc: skip atomic refcount for uncloned buffers
  io_uring/mock: add trivial poll handler
  io_uring/mock: support for async read/write
  io_uring/mock: allow to choose FMODE_NOWAIT
  io_uring/mock: add sync read/write
  io_uring/mock: add cmd using vectored regbufs
  io_uring/mock: add basic infra for test mock files
  io_uring: remove errant ';' from IORING_CQE_F_TSTAMP_HW definition
  io_uring/netcmd: add tx timestamping cmd support
  io_uring: add mshot helper for posting CQE32
  io_uring/cmd: allow multishot polled commands
  io_uring/poll: introduce io_arm_apoll()
  io_uring/nop: add IORING_NOP_TW completion flag
  io_uring/uring_cmd: implement ->sqe_copy() to avoid unnecessary copies
  io_uring/uring_cmd: get rid of io_uring_cmd_prep_setup()
  io_uring: add struct io_cold_def->sqe_copy() method
  io_uring: add IO_URING_F_INLINE issue flag
  net: timestamp: add helper returning skb's tx tstamp
* for-6.17/block: (38 commits)
  block: remove pktcdvd driver
  ublk: introduce and use ublk_set_canceling helper
  ublk: speed up ublk server exit handling
  zram: pass buffer offset to zcomp_available_show()
  block: zram: replace scnprintf() with sysfs_emit() in *_show() functions
  bcache: switch from pages to folios in read_super()
  virtio: blk/scsi: use block layer helpers to calculate num of queues
  scsi: use block layer helpers to calculate num of queues
  nvme-pci: use block layer helpers to calculate num of queues
  blk-mq: add number of queue calc helper
  lib/group_cpus: Let group_cpu_evenly() return the number of initialized masks
  ublk: cache-align struct ublk_io
  ublk: remove ubq checks from ublk_{get,put}_req_ref()
  ublk: optimize UBLK_IO_UNREGISTER_IO_BUF on daemon task
  ublk: optimize UBLK_IO_REGISTER_IO_BUF on daemon task
  ublk: return early if blk_should_fake_timeout()
  ublk: allow UBLK_IO_(UN)REGISTER_IO_BUF on any task
  ublk: don't take ublk_queue in ublk_unregister_io_buf()
  ublk: consolidate UBLK_IO_FLAG_{ACTIVE,OWNED_BY_SRV} checks
  ublk: remove task variable from __ublk_ch_uring_cmd()
  ...
* for-6.17/block:
  nvme-pci: fix dma unmapping when using PRPs and not using the IOVA mapping
* for-6.17/block:
  Documentation: remove reference to pktcdvd in cdrom documentation
* io_uring-6.16:
  Revert "io_uring: gate REQ_F_ISREG on !S_ANON_INODE as well"
  io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU
* for-6.17/block:
  block: mtip32xx: Fix usage of dma_map_sg()
* for-6.17/block:
  drbd: add missing kref_get in handle_write_conflicts
* for-6.17/io_uring:
  io_uring/zcrx: prepare fallback for larger pages
  io_uring/zcrx: assert area type in io_zcrx_iov_page
  io_uring/zcrx: allocate sgtable for umem areas
  io_uring/zcrx: introduce io_populate_area_dma
  io_uring/zcrx: return error from io_zcrx_map_area_*
  io_uring/zcrx: always pass page to io_zcrx_copy_chunk
* for-6.17/block:
  nbd: fix lockdep deadlock warning
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blktests-ci Bot commented Jul 10, 2025

Upstream branch: f4ca523
series: https://patchwork.kernel.org/project/linux-block/list/?series=980640
version: 1

Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/linux-block/list/?series=980640
error message:

Cmd('git') failed due to: exit code(128)
  cmdline: git am --3way
  stdout: 'Applying: block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()
Patch failed at 0001 block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()'
  stderr: 'error: sha1 information is lacking or useless (block/ioctl.c).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"'

conflict:


@blktests-ci blktests-ci Bot force-pushed the for-next_base branch 3 times, most recently from 8784bb4 to 059d7e3 Compare July 11, 2025 07:05
@blktests-ci blktests-ci Bot added V2 and removed V1 labels Jul 11, 2025
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blktests-ci Bot pushed a commit that referenced this pull request Aug 2, 2025
Without the change `perf `hangs up on charaster devices. On my system
it's enough to run system-wide sampler for a few seconds to get the
hangup:

    $ perf record -a -g --call-graph=dwarf
    $ perf report
    # hung

`strace` shows that hangup happens on reading on a character device
`/dev/dri/renderD128`

    $ strace -y -f -p 2780484
    strace: Process 2780484 attached
    pread64(101</dev/dri/renderD128>, strace: Process 2780484 detached

It's call trace descends into `elfutils`:

    $ gdb -p 2780484
    (gdb) bt
    #0  0x00007f5e508f04b7 in __libc_pread64 (fd=101, buf=0x7fff9df7edb0, count=0, offset=0)
        at ../sysdeps/unix/sysv/linux/pread64.c:25
    #1  0x00007f5e52b79515 in read_file () from /<<NIX>>/elfutils-0.192/lib/libelf.so.1
    #2  0x00007f5e52b25666 in libdw_open_elf () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #3  0x00007f5e52b25907 in __libdw_open_file () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #4  0x00007f5e52b120a9 in dwfl_report_elf@@ELFUTILS_0.156 ()
       from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #5  0x000000000068bf20 in __report_module (al=al@entry=0x7fff9df80010, ip=ip@entry=139803237033216, ui=ui@entry=0x5369b5e0)
        at util/dso.h:537
    #6  0x000000000068c3d1 in report_module (ip=139803237033216, ui=0x5369b5e0) at util/unwind-libdw.c:114
    #7  frame_callback (state=0x535aef10, arg=0x5369b5e0) at util/unwind-libdw.c:242
    #8  0x00007f5e52b261d3 in dwfl_thread_getframes () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #9  0x00007f5e52b25bdb in get_one_thread_cb () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #10 0x00007f5e52b25faa in dwfl_getthreads () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #11 0x00007f5e52b26514 in dwfl_getthread_frames () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #12 0x000000000068c6ce in unwind__get_entries (cb=cb@entry=0x5d4620 <unwind_entry>, arg=arg@entry=0x10cd5fa0,
        thread=thread@entry=0x1076a290, data=data@entry=0x7fff9df80540, max_stack=max_stack@entry=127,
        best_effort=best_effort@entry=false) at util/thread.h:152
    #13 0x00000000005dae95 in thread__resolve_callchain_unwind (evsel=0x106006d0, thread=0x1076a290, cursor=0x10cd5fa0,
        sample=0x7fff9df80540, max_stack=127, symbols=true) at util/machine.c:2939
    #14 thread__resolve_callchain_unwind (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, sample=0x7fff9df80540,
        max_stack=127, symbols=true) at util/machine.c:2920
    #15 __thread__resolve_callchain (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, evsel@entry=0x7fff9df80440,
        sample=0x7fff9df80540, parent=parent@entry=0x7fff9df804a0, root_al=root_al@entry=0x7fff9df80440, max_stack=127, symbols=true)
        at util/machine.c:2970
    #16 0x00000000005d0cb2 in thread__resolve_callchain (thread=<optimized out>, cursor=<optimized out>, evsel=0x7fff9df80440,
        sample=<optimized out>, parent=0x7fff9df804a0, root_al=0x7fff9df80440, max_stack=127) at util/machine.h:198
    #17 sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fff9df804a0,
        evsel=evsel@entry=0x106006d0, al=al@entry=0x7fff9df80440, max_stack=max_stack@entry=127) at util/callchain.c:1127
    #18 0x0000000000617e08 in hist_entry_iter__add (iter=iter@entry=0x7fff9df80480, al=al@entry=0x7fff9df80440, max_stack_depth=127,
        arg=arg@entry=0x7fff9df81ae0) at util/hist.c:1255
    #19 0x000000000045d2d0 in process_sample_event (tool=0x7fff9df81ae0, event=<optimized out>, sample=0x7fff9df80540,
        evsel=0x106006d0, machine=<optimized out>) at builtin-report.c:334
    #20 0x00000000005e3bb1 in perf_session__deliver_event (session=0x105ff2c0, event=0x7f5c7d735ca0, tool=0x7fff9df81ae0,
        file_offset=2914716832, file_path=0x105ffbf0 "perf.data") at util/session.c:1367
    #21 0x00000000005e8d93 in do_flush (oe=0x105ffa50, show_progress=false) at util/ordered-events.c:245
    #22 __ordered_events__flush (oe=0x105ffa50, how=OE_FLUSH__ROUND, timestamp=<optimized out>) at util/ordered-events.c:324
    #23 0x00000000005e1f64 in perf_session__process_user_event (session=0x105ff2c0, event=0x7f5c7d752b18, file_offset=2914835224,
        file_path=0x105ffbf0 "perf.data") at util/session.c:1419
    #24 0x00000000005e47c7 in reader__read_event (rd=rd@entry=0x7fff9df81260, session=session@entry=0x105ff2c0,
    --Type <RET> for more, q to quit, c to continue without paging--
    quit
        prog=prog@entry=0x7fff9df81220) at util/session.c:2132
    #25 0x00000000005e4b37 in reader__process_events (rd=0x7fff9df81260, session=0x105ff2c0, prog=0x7fff9df81220)
        at util/session.c:2181
    #26 __perf_session__process_events (session=0x105ff2c0) at util/session.c:2226
    #27 perf_session__process_events (session=session@entry=0x105ff2c0) at util/session.c:2390
    #28 0x0000000000460add in __cmd_report (rep=0x7fff9df81ae0) at builtin-report.c:1076
    #29 cmd_report (argc=<optimized out>, argv=<optimized out>) at builtin-report.c:1827
    #30 0x00000000004c5a40 in run_builtin (p=p@entry=0xd8f7f8 <commands+312>, argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0)
        at perf.c:351
    #31 0x00000000004c5d63 in handle_internal_command (argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0) at perf.c:404
    #32 0x0000000000442de3 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:448
    #33 main (argc=<optimized out>, argv=0x7fff9df844b0) at perf.c:556

The hangup happens because nothing in` perf` or `elfutils` checks if a
mapped file is easily readable.

The change conservatively skips all non-regular files.

Signed-off-by: Sergei Trofimovich <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
@blktests-ci blktests-ci Bot force-pushed the for-next_base branch 3 times, most recently from 62f402e to ca24d57 Compare August 8, 2025 12:50
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blktests-ci Bot commented Aug 10, 2025

At least one diff in series https://patchwork.kernel.org/project/linux-block/list/?series=980640 irrelevant now for [{'archived': False, 'project': 241}] search patterns

@blktests-ci blktests-ci Bot closed this Aug 10, 2025
@blktests-ci blktests-ci Bot deleted the series/980640=>for-next branch August 20, 2025 12:05
blktests-ci Bot pushed a commit that referenced this pull request Sep 29, 2025
When the PAGEMAP_SCAN ioctl is invoked with vec_len = 0 reaches
pagemap_scan_backout_range(), kernel panics with null-ptr-deref:

[   44.936808] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[   44.937797] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
[   44.938391] CPU: 1 UID: 0 PID: 2480 Comm: reproducer Not tainted 6.17.0-rc6 #22 PREEMPT(none)
[   44.939062] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   44.939935] RIP: 0010:pagemap_scan_thp_entry.isra.0+0x741/0xa80

<snip registers, unreliable trace>

[   44.946828] Call Trace:
[   44.947030]  <TASK>
[   44.949219]  pagemap_scan_pmd_entry+0xec/0xfa0
[   44.952593]  walk_pmd_range.isra.0+0x302/0x910
[   44.954069]  walk_pud_range.isra.0+0x419/0x790
[   44.954427]  walk_p4d_range+0x41e/0x620
[   44.954743]  walk_pgd_range+0x31e/0x630
[   44.955057]  __walk_page_range+0x160/0x670
[   44.956883]  walk_page_range_mm+0x408/0x980
[   44.958677]  walk_page_range+0x66/0x90
[   44.958984]  do_pagemap_scan+0x28d/0x9c0
[   44.961833]  do_pagemap_cmd+0x59/0x80
[   44.962484]  __x64_sys_ioctl+0x18d/0x210
[   44.962804]  do_syscall_64+0x5b/0x290
[   44.963111]  entry_SYSCALL_64_after_hwframe+0x76/0x7e

vec_len = 0 in pagemap_scan_init_bounce_buffer() means no buffers are
allocated and p->vec_buf remains set to NULL.

This breaks an assumption made later in pagemap_scan_backout_range(), that
page_region is always allocated for p->vec_buf_index.

Fix it by explicitly checking p->vec_buf for NULL before dereferencing.

Other sites that might run into same deref-issue are already (directly or
transitively) protected by checking p->vec_buf.

Note:
From PAGEMAP_SCAN man page, it seems vec_len = 0 is valid when no output
is requested and it's only the side effects caller is interested in,
hence it passes check in pagemap_scan_get_args().

This issue was found by syzkaller.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 52526ca ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: Jakub Acs <[email protected]>
Reviewed-by: Muhammad Usama Anjum <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Jinjiang Tu <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Penglei Jiang <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Andrei Vagin <[email protected]>
Cc: "Michał Mirosław" <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Oct 23, 2025
Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while
the overlayfs is being unmounted, can lead to dereferencing NULL ptr.

This issue was found by syzkaller.

Race Condition Diagram:

Thread 1                           Thread 2
--------                           --------

generic_shutdown_super()
 shrink_dcache_for_umount
  sb->s_root = NULL

                    |
                    |             vfs_read()
                    |              inotify_fdinfo()
                    |               * inode get from mark *
                    |               show_mark_fhandle(m, inode)
                    |                exportfs_encode_fid(inode, ..)
                    |                 ovl_encode_fh(inode, ..)
                    |                  ovl_check_encode_origin(inode)
                    |                   * deref i_sb->s_root *
                    |
                    |
                    v
 fsnotify_sb_delete(sb)

Which then leads to:

[   32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[   32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
[   32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)

<snip registers, unreliable trace>

[   32.143353] Call Trace:
[   32.143732]  ovl_encode_fh+0xd5/0x170
[   32.144031]  exportfs_encode_inode_fh+0x12f/0x300
[   32.144425]  show_mark_fhandle+0xbe/0x1f0
[   32.145805]  inotify_fdinfo+0x226/0x2d0
[   32.146442]  inotify_show_fdinfo+0x1c5/0x350
[   32.147168]  seq_show+0x530/0x6f0
[   32.147449]  seq_read_iter+0x503/0x12a0
[   32.148419]  seq_read+0x31f/0x410
[   32.150714]  vfs_read+0x1f0/0x9e0
[   32.152297]  ksys_read+0x125/0x240

IOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set
to NULL in the unmount path.

Fix it by protecting calling exportfs_encode_fid() from
show_mark_fhandle() with s_umount lock.

This form of fix was suggested by Amir in [1].

[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/

Fixes: c45beeb ("ovl: support encoding fid from inode with no alias")
Signed-off-by: Jakub Acs <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Amir Goldstein <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Jan Kara <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Nov 14, 2025
Typically copynotify stateid is freed either when parent's stateid
is being close/freed or in nfsd4_laundromat if the stateid hasn't
been used in a lease period.

However, in case when the server got an OPEN (which created
a parent stateid), followed by a COPY_NOTIFY using that stateid,
followed by a client reboot. New client instance while doing
CREATE_SESSION would force expire previous state of this client.
It leads to the open state being freed thru release_openowner->
nfs4_free_ol_stateid() and it finds that it still has copynotify
stateid associated with it. We currently print a warning and is
triggerred

WARNING: CPU: 1 PID: 8858 at fs/nfsd/nfs4state.c:1550 nfs4_free_ol_stateid+0xb0/0x100 [nfsd]

This patch, instead, frees the associated copynotify stateid here.

If the parent stateid is freed (without freeing the copynotify
stateids associated with it), it leads to the list corruption
when laundromat ends up freeing the copynotify state later.

[ 1626.839430] Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
[ 1626.842828] Modules linked in: nfnetlink_queue nfnetlink_log bluetooth cfg80211 rpcrdma rdma_cm iw_cm ib_cm ib_core nfsd nfs_acl lockd grace nfs_localio ext4 crc16 mbcache jbd2 overlay uinput snd_seq_dummy snd_hrtimer qrtr rfkill vfat fat uvcvideo snd_hda_codec_generic videobuf2_vmalloc videobuf2_memops snd_hda_intel uvc snd_intel_dspcfg videobuf2_v4l2 videobuf2_common snd_hda_codec snd_hda_core videodev snd_hwdep snd_seq mc snd_seq_device snd_pcm snd_timer snd soundcore sg loop auth_rpcgss vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vmw_vmci vsock xfs 8021q garp stp llc mrp nvme ghash_ce e1000e nvme_core sr_mod nvme_keyring nvme_auth cdrom vmwgfx drm_ttm_helper ttm sunrpc dm_mirror dm_region_hash dm_log iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi fuse dm_multipath dm_mod nfnetlink
[ 1626.855594] CPU: 2 UID: 0 PID: 199 Comm: kworker/u24:33 Kdump: loaded Tainted: G    B   W           6.17.0-rc7+ #22 PREEMPT(voluntary)
[ 1626.857075] Tainted: [B]=BAD_PAGE, [W]=WARN
[ 1626.857573] Hardware name: VMware, Inc. VMware20,1/VBSA, BIOS VMW201.00V.24006586.BA64.2406042154 06/04/2024
[ 1626.858724] Workqueue: nfsd4 laundromat_main [nfsd]
[ 1626.859304] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 1626.860010] pc : __list_del_entry_valid_or_report+0x148/0x200
[ 1626.860601] lr : __list_del_entry_valid_or_report+0x148/0x200
[ 1626.861182] sp : ffff8000881d7a40
[ 1626.861521] x29: ffff8000881d7a40 x28: 0000000000000018 x27: ffff0000c2a98200
[ 1626.862260] x26: 0000000000000600 x25: 0000000000000000 x24: ffff8000881d7b20
[ 1626.862986] x23: ffff0000c2a981e8 x22: 1fffe00012410e7d x21: ffff0000920873e8
[ 1626.863701] x20: ffff0000920873e8 x19: ffff000086f22998 x18: 0000000000000000
[ 1626.864421] x17: 20747562202c3839 x16: 3932326636383030 x15: 3030666666662065
[ 1626.865092] x14: 6220646c756f6873 x13: 0000000000000001 x12: ffff60004fd9e4a3
[ 1626.865713] x11: 1fffe0004fd9e4a2 x10: ffff60004fd9e4a2 x9 : dfff800000000000
[ 1626.866320] x8 : 00009fffb0261b5e x7 : ffff00027ecf2513 x6 : 0000000000000001
[ 1626.866938] x5 : ffff00027ecf2510 x4 : ffff60004fd9e4a3 x3 : 0000000000000000
[ 1626.867553] x2 : 0000000000000000 x1 : ffff000096069640 x0 : 000000000000006d
[ 1626.868167] Call trace:
[ 1626.868382]  __list_del_entry_valid_or_report+0x148/0x200 (P)
[ 1626.868876]  _free_cpntf_state_locked+0xd0/0x268 [nfsd]
[ 1626.869368]  nfs4_laundromat+0x6f8/0x1058 [nfsd]
[ 1626.869813]  laundromat_main+0x24/0x60 [nfsd]
[ 1626.870231]  process_one_work+0x584/0x1050
[ 1626.870595]  worker_thread+0x4c4/0xc60
[ 1626.870893]  kthread+0x2f8/0x398
[ 1626.871146]  ret_from_fork+0x10/0x20
[ 1626.871422] Code: aa1303e1 aa1403e3 910e8000 97bc55d7 (d4210000)
[ 1626.871892] SMP: stopping secondary CPUs

Reported-by: [email protected]
Closes: https://lore.kernel.org/linux-nfs/[email protected]/T/#t
Fixes: 624322f ("NFSD add COPY_NOTIFY operation")
Cc: [email protected]
Signed-off-by: Olga Kornievskaia <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Mar 5, 2026
Syzkaller managed to find a combination of actions that was generating
this warning:

  msk->pm.local_addr_used == 0
  WARNING: net/mptcp/pm_kernel.c:1071 at __mark_subflow_endp_available net/mptcp/pm_kernel.c:1071 [inline], CPU#1: syz.2.17/961
  WARNING: net/mptcp/pm_kernel.c:1071 at mptcp_nl_remove_subflow_and_signal_addr net/mptcp/pm_kernel.c:1103 [inline], CPU#1: syz.2.17/961
  WARNING: net/mptcp/pm_kernel.c:1071 at mptcp_pm_nl_del_addr_doit+0x81d/0x8f0 net/mptcp/pm_kernel.c:1210, CPU#1: syz.2.17/961
  Modules linked in:
  CPU: 1 UID: 0 PID: 961 Comm: syz.2.17 Not tainted 6.19.0-08368-gfafda3b4b06b #22 PREEMPT(full)
  Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.17.0-debian-1.17.0-1build1 04/01/2014
  RIP: 0010:__mark_subflow_endp_available net/mptcp/pm_kernel.c:1071 [inline]
  RIP: 0010:mptcp_nl_remove_subflow_and_signal_addr net/mptcp/pm_kernel.c:1103 [inline]
  RIP: 0010:mptcp_pm_nl_del_addr_doit+0x81d/0x8f0 net/mptcp/pm_kernel.c:1210
  Code: 89 c5 e8 46 30 6f fe e9 21 fd ff ff 49 83 ed 80 e8 38 30 6f fe 4c 89 ef be 03 00 00 00 e8 db 49 df fe eb ac e8 24 30 6f fe 90 <0f> 0b 90 e9 1d ff ff ff e8 16 30 6f fe eb 05 e8 0f 30 6f fe e8 9a
  RSP: 0018:ffffc90001663880 EFLAGS: 00010293
  RAX: ffffffff82de1a6c RBX: 0000000000000000 RCX: ffff88800722b500
  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
  RBP: ffff8880158b22d0 R08: 0000000000010425 R09: ffffffffffffffff
  R10: ffffffff82de18ba R11: 0000000000000000 R12: ffff88800641a640
  R13: ffff8880158b1880 R14: ffff88801ec3c900 R15: ffff88800641a650
  FS:  00005555722c3500(0000) GS:ffff8880f909d000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f66346e0f60 CR3: 000000001607c000 CR4: 0000000000350ef0
  Call Trace:
   <TASK>
   genl_family_rcv_msg_doit+0x117/0x180 net/netlink/genetlink.c:1115
   genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
   genl_rcv_msg+0x3a8/0x3f0 net/netlink/genetlink.c:1210
   netlink_rcv_skb+0x16d/0x240 net/netlink/af_netlink.c:2550
   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
   netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
   netlink_unicast+0x3e9/0x4c0 net/netlink/af_netlink.c:1344
   netlink_sendmsg+0x4aa/0x5b0 net/netlink/af_netlink.c:1894
   sock_sendmsg_nosec net/socket.c:727 [inline]
   __sock_sendmsg+0xc9/0xf0 net/socket.c:742
   ____sys_sendmsg+0x272/0x3b0 net/socket.c:2592
   ___sys_sendmsg+0x2de/0x320 net/socket.c:2646
   __sys_sendmsg net/socket.c:2678 [inline]
   __do_sys_sendmsg net/socket.c:2683 [inline]
   __se_sys_sendmsg net/socket.c:2681 [inline]
   __x64_sys_sendmsg+0x110/0x1a0 net/socket.c:2681
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x143/0x440 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x7f66346f826d
  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 e8 ff ff ff f7 d8 64 89 01 48
  RSP: 002b:00007ffc83d8bdc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
  RAX: ffffffffffffffda RBX: 00007f6634985fa0 RCX: 00007f66346f826d
  RDX: 00000000040000b0 RSI: 0000200000000740 RDI: 0000000000000007
  RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6634985fa8
  R13: 00007f6634985fac R14: 0000000000000000 R15: 0000000000001770
   </TASK>

The actions that caused that seem to be:

 - Set the MPTCP subflows limit to 0
 - Create an MPTCP endpoint with both the 'signal' and 'subflow' flags
 - Create a new MPTCP connection from a different address: an ADD_ADDR
   linked to the MPTCP endpoint will be sent ('signal' flag), but no
   subflows is initiated ('subflow' flag)
 - Remove the MPTCP endpoint

In this case, msk->pm.local_addr_used has been kept to 0 -- because no
subflows have been created -- but the corresponding bit in
msk->pm.id_avail_bitmap has been cleared when the ADD_ADDR has been
sent. This later causes a splat when removing the MPTCP endpoint because
msk->pm.local_addr_used has been kept to 0.

Now, if an endpoint has both the signal and subflow flags, but it is not
possible to create subflows because of the limits or the c-flag case,
then the local endpoint counter is still incremented: the endpoint is
used at the end. This avoids issues later when removing the endpoint and
calling __mark_subflow_endp_available(), which expects
msk->pm.local_addr_used to have been previously incremented if the
endpoint was marked as used according to msk->pm.id_avail_bitmap.

Note that signal_and_subflow variable is reset to false when the limits
and the c-flag case allows subflows creation. Also, local_addr_used is
only incremented for non ID0 subflows.

Fixes: 85df533 ("mptcp: pm: do not ignore 'subflow' if 'signal' flag is also set")
Cc: [email protected]
Closes: multipath-tcp/mptcp_net-next#613
Reviewed-by: Mat Martineau <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/20260303-net-mptcp-misc-fixes-7-0-rc2-v1-4-4b5462b6f016@kernel.org
Signed-off-by: Jakub Kicinski <[email protected]>
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