linux-stable.git/fs/afs, branch linux-6.13.y

afs: Give an afs_server object a ref on the afs_cell object it points to

2025-03-07T17:26:57+00:00

[ Upstream commit 1f0fc3374f3345ff1d150c5c56ac5016e5d3826a ]

Give an afs_server object a ref on the afs_cell object it points to so that
the cell doesn't get deleted before the server record.

Whilst this is circular (cell -> vol -> server_list -> server -> cell), the
ref only pins the memory, not the lifetime as that's controlled by the
activity counter.  When the volume's activity counter reaches 0, it
detaches from the cell and discards its server list; when a cell's activity
counter reaches 0, it discards its root volume.  At that point, the
circularity is cut.

Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: Simon Horman 
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20250218192250.296870-6-dhowells@redhat.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

afs: Fix the server_list to unuse a displaced server rather than putting it

2025-03-07T17:26:57+00:00

[ Upstream commit add117e48df4788a86a21bd0515833c0a6db1ad1 ]

When allocating and building an afs_server_list struct object from a VLDB
record, we look up each server address to get the server record for it -
but a server may have more than one entry in the record and we discard the
duplicate pointers.  Currently, however, when we discard, we only put a
server record, not unuse it - but the lookup got as an active-user count.

The active-user count on an afs_server_list object determines its lifetime
whereas the refcount keeps the memory backing it around.  Failing to reduce
the active-user counter prevents the record from being cleaned up and can
lead to multiple copied being seen - and pointing to deleted afs_cell
objects and other such things.

Fix this by switching the incorrect 'put' to an 'unuse' instead.

Without this, occasionally, a dead server record can be seen in
/proc/net/afs/servers and list corruption may be observed:

    list_del corruption. prev->next should be ffff888102423e40, but was 0000000000000000. (prev=ffff88810140cd38)

Fixes: 977e5f8ed0ab ("afs: Split the usage count on struct afs_server")
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: Simon Horman 
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20250218192250.296870-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

afs: Fix the fallback handling for the YFS.RemoveFile2 RPC call

2025-02-08T09:00:57+00:00

[ Upstream commit e30458d690f35abb01de8b3cbc09285deb725d00 ]

Fix a pair of bugs in the fallback handling for the YFS.RemoveFile2 RPC
call:

 (1) Fix the abort code check to also look for RXGEN_OPCODE.  The lack of
     this masks the second bug.

 (2) call->server is now not used for ordinary filesystem RPC calls that
     have an operation descriptor.  Fix to use call->op->server instead.

Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/109541.1736865963@warthog.procyon.org.uk
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

afs: Fix cleanup of immediately failed async calls

2025-02-08T09:00:53+00:00

[ Upstream commit 9750be93b2be12b6d92323b97d7c055099d279e6 ]

If we manage to begin an async call, but fail to transmit any data on it
due to a signal, we then abort it which causes a race between the
notification of call completion from rxrpc and our attempt to cancel the
notification.  The notification will be necessary, however, for async
FetchData to terminate the netfs subrequest.

However, since we get a notification from rxrpc upon completion of a call
(aborted or otherwise), we can just leave it to that.

This leads to calls not getting cleaned up, but appearing in
/proc/net/rxrpc/calls as being aborted with code 6.

Fix this by making the "error_do_abort:" case of afs_make_call() abort the
call and then abandon it to the notification handler.

Fixes: 34fa47612bfe ("afs: Fix race in async call refcounting")
Reported-by: Marc Dionne 
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241216204124.3752367-25-dhowells@redhat.com
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

afs: Fix directory format encoding struct

2025-02-08T09:00:53+00:00

[ Upstream commit 07a10767853adcbdbf436dc91393b729b52c4e81 ]

The AFS directory format structure, union afs_xdr_dir_block::meta, has too
many alloc counter slots declared and so pushes the hash table along and
over the data.  This doesn't cause a problem at the moment because I'm
currently ignoring the hash table and only using the correct number of
alloc_ctrs in the code anyway.  In future, however, I should start using
the hash table to try and speed up afs_lookup().

Fix this by using the correct constant to declare the counter array.

Fixes: 4ea219a839bf ("afs: Split the directory content defs into a header")
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241216204124.3752367-14-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

afs: Fix EEXIST error returned from afs_rmdir() to be ENOTEMPTY

2025-02-08T09:00:53+00:00

[ Upstream commit b49194da2aff2c879dec9c59ef8dec0f2b0809ef ]

AFS servers pass back a code indicating EEXIST when they're asked to remove
a directory that is not empty rather than ENOTEMPTY because not all the
systems that an AFS server can run on have the latter error available and
AFS preexisted the addition of that error in general.

Fix afs_rmdir() to translate EEXIST to ENOTEMPTY.

Fixes: 260a980317da ("[AFS]: Add "directory write" support.")
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241216204124.3752367-13-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

afs: Fix merge preference rule failure condition

2025-01-09T16:21:41+00:00

syzbot reported a lock held when returning to userspace[1].  This is
because if argc is less than 0 and the function returns directly, the held
inode lock is not released.

Fix this by store the error in ret and jump to done to clean up instead of
returning directly.

[dh: Modified Lizhi Xu's original patch to make it honour the error code
from afs_split_string()]

[1]
WARNING: lock held when returning to user space!
6.13.0-rc3-syzkaller-00209-g499551201b5f #0 Not tainted
------------------------------------------------
syz-executor133/5823 is leaving the kernel with locks still held!
1 lock held by syz-executor133/5823:
 #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: afs_proc_addr_prefs_write+0x2bb/0x14e0 fs/afs/addr_prefs.c:388

Reported-by: syzbot+76f33569875eb708e575@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=76f33569875eb708e575
Signed-off-by: Lizhi Xu 
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241226012616.2348907-1-lizhi.xu@windriver.com/
Link: https://lore.kernel.org/r/529850.1736261552@warthog.procyon.org.uk
Tested-by: syzbot+76f33569875eb708e575@syzkaller.appspotmail.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner

afs: Fix the maximum cell name length

2025-01-07T14:55:25+00:00

The kafs filesystem limits the maximum length of a cell to 256 bytes, but a
problem occurs if someone actually does that: kafs tries to create a
directory under /proc/net/afs/ with the name of the cell, but that fails
with a warning:

        WARNING: CPU: 0 PID: 9 at fs/proc/generic.c:405

because procfs limits the maximum filename length to 255.

However, the DNS limits the maximum lookup length and, by extension, the
maximum cell name, to 255 less two (length count and trailing NUL).

Fix this by limiting the maximum acceptable cellname length to 253.  This
also allows us to be sure we can create the "/afs/./" mountpoint too.

Further, split the YFS VL record cell name maximum to be the 256 allowed by
the protocol and ignore the record retrieved by YFSVL.GetCellName if it
exceeds 253.

Fixes: c3e9f888263b ("afs: Implement client support for the YFSVL.GetCellName RPC op")
Reported-by: syzbot+7848fee1f1e5c53f912b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/6776d25d.050a0220.3a8527.0048.GAE@google.com/
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/376236.1736180460@warthog.procyon.org.uk
Tested-by: syzbot+7848fee1f1e5c53f912b@syzkaller.appspotmail.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner

netfs: Work around recursion by abandoning retry if nothing read

2024-12-20T21:07:57+00:00

syzkaller reported recursion with a loop of three calls (netfs_rreq_assess,
netfs_retry_reads and netfs_rreq_terminated) hitting the limit of the stack
during an unbuffered or direct I/O read.

There are a number of issues:

 (1) There is no limit on the number of retries.

 (2) A subrequest is supposed to be abandoned if it does not transfer
     anything (NETFS_SREQ_NO_PROGRESS), but that isn't checked under all
     circumstances.

 (3) The actual root cause, which is this:

	if (atomic_dec_and_test(&rreq->nr_outstanding))
		netfs_rreq_terminated(rreq, ...);

     When we do a retry, we bump the rreq->nr_outstanding counter to
     prevent the final cleanup phase running before we've finished
     dispatching the retries.  The problem is if we hit 0, we have to do
     the cleanup phase - but we're in the cleanup phase and end up
     repeating the retry cycle, hence the recursion.

Work around the problem by limiting the number of retries.  This is based
on Lizhi Xu's patch[1], and makes the following changes:

 (1) Replace NETFS_SREQ_NO_PROGRESS with NETFS_SREQ_MADE_PROGRESS and make
     the filesystem set it if it managed to read or write at least one byte
     of data.  Clear this bit before issuing a subrequest.

 (2) Add a ->retry_count member to the subrequest and increment it any time
     we do a retry.

 (3) Remove the NETFS_SREQ_RETRYING flag as it is superfluous with
     ->retry_count.  If the latter is non-zero, we're doing a retry.

 (4) Abandon a subrequest if retry_count is non-zero and we made no
     progress.

 (5) Use ->retry_count in both the write-side and the read-size.

[?] Question: Should I set a hard limit on retry_count in both read and
    write?  Say it hits 50, we always abandon it.  The problem is that
    these changes only mitigate the issue.  As long as it made at least one
    byte of progress, the recursion is still an issue.  This patch
    mitigates the problem, but does not fix the underlying cause.  I have
    patches that will do that, but it's an intrusive fix that's currently
    pending for the next merge window.

The oops generated by KASAN looks something like:

   BUG: TASK stack guard page was hit at ffffc9000482ff48 (stack is ffffc90004830000..ffffc90004838000)
   Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN NOPTI
   ...
   RIP: 0010:mark_lock+0x25/0xc60 kernel/locking/lockdep.c:4686
    ...
    mark_usage kernel/locking/lockdep.c:4646 [inline]
    __lock_acquire+0x906/0x3ce0 kernel/locking/lockdep.c:5156
    lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
    local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
    ___slab_alloc+0x123/0x1880 mm/slub.c:3695
    __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3908
    __slab_alloc_node mm/slub.c:3961 [inline]
    slab_alloc_node mm/slub.c:4122 [inline]
    kmem_cache_alloc_noprof+0x2a7/0x2f0 mm/slub.c:4141
    radix_tree_node_alloc.constprop.0+0x1e8/0x350 lib/radix-tree.c:253
    idr_get_free+0x528/0xa40 lib/radix-tree.c:1506
    idr_alloc_u32+0x191/0x2f0 lib/idr.c:46
    idr_alloc+0xc1/0x130 lib/idr.c:87
    p9_tag_alloc+0x394/0x870 net/9p/client.c:321
    p9_client_prepare_req+0x19f/0x4d0 net/9p/client.c:644
    p9_client_zc_rpc.constprop.0+0x105/0x880 net/9p/client.c:793
    p9_client_read_once+0x443/0x820 net/9p/client.c:1570
    p9_client_read+0x13f/0x1b0 net/9p/client.c:1534
    v9fs_issue_read+0x115/0x310 fs/9p/vfs_addr.c:74
    netfs_retry_read_subrequests fs/netfs/read_retry.c:60 [inline]
    netfs_retry_reads+0x153a/0x1d00 fs/netfs/read_retry.c:232
    netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
    netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
    netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
    netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
    netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
    netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
    netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
    ...
    netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
    netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
    netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
    netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
    netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
    netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
    netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
    netfs_dispatch_unbuffered_reads fs/netfs/direct_read.c:103 [inline]
    netfs_unbuffered_read fs/netfs/direct_read.c:127 [inline]
    netfs_unbuffered_read_iter_locked+0x12f6/0x19b0 fs/netfs/direct_read.c:221
    netfs_unbuffered_read_iter+0xc5/0x100 fs/netfs/direct_read.c:256
    v9fs_file_read_iter+0xbf/0x100 fs/9p/vfs_file.c:361
    do_iter_readv_writev+0x614/0x7f0 fs/read_write.c:832
    vfs_readv+0x4cf/0x890 fs/read_write.c:1025
    do_preadv fs/read_write.c:1142 [inline]
    __do_sys_preadv fs/read_write.c:1192 [inline]
    __se_sys_preadv fs/read_write.c:1187 [inline]
    __x64_sys_preadv+0x22d/0x310 fs/read_write.c:1187
    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
    do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Closes: https://syzkaller.appspot.com/bug?extid=1fc6f64c40a9d143cfb6
Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241108034020.3695718-1-lizhi.xu@windriver.com/ [1]
Link: https://lore.kernel.org/r/20241213135013.2964079-9-dhowells@redhat.com
Tested-by: syzbot+885c03ad650731743489@syzkaller.appspotmail.com
Suggested-by: Lizhi Xu 
cc: Dominique Martinet 
cc: Jeff Layton 
cc: v9fs@lists.linux.dev
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Reported-by: syzbot+885c03ad650731743489@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner

Merge tag 'vfs-6.12-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

2024-11-01T17:37:10+00:00

Pull filesystem fixes from Christian Brauner:
 "VFS:

   - Fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP=y is set

   - Add a get_tree_bdev_flags() helper that allows to modify e.g.,
     whether errors are logged into the filesystem context during
     superblock creation. This is used by erofs to fix a userspace
     regression where an error is currently logged when its used on a
     regular file which is an new allowed mode in erofs.

  netfs:

   - Fix the sysfs debug path in the documentation.

   - Fix iov_iter_get_pages*() for folio queues by skipping the page
     extracation if we're at the end of a folio.

  afs:

   - Fix moving subdirectories to different parent directory.

  autofs:

   - Fix handling of AUTOFS_DEV_IOCTL_TIMEOUT_CMD ioctl in
     validate_dev_ioctl(). The actual ioctl number, not the ioctl
     command needs to be checked for autofs"

* tag 'vfs-6.12-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP
  autofs: fix thinko in validate_dev_ioctl()
  iov_iter: Fix iov_iter_get_pages*() for folio_queue
  afs: Fix missing subdir edit when renamed between parent dirs
  doc: correcting the debug path for cachefiles
  erofs: use get_tree_bdev_flags() to avoid misleading messages
  fs/super.c: introduce get_tree_bdev_flags()