linux.git/fs/ceph, branch v6.12.80

ceph: fix memory leaks in ceph_mdsc_build_path()

2026-03-25T10:08:33+00:00

commit 040d159a45ded7f33201421a81df0aa2a86e5a0b upstream.

Add __putname() calls to error code paths that did not free the "path"
pointer obtained by __getname().  If ownership of this pointer is not
passed to the caller via path_info.path, the function must free it
before returning.

Cc: stable@vger.kernel.org
Fixes: 3fd945a79e14 ("ceph: encode encrypted name in ceph_mdsc_build_path and dentry release")
Fixes: 550f7ca98ee0 ("ceph: give up on paths longer than PATH_MAX")
Signed-off-by: Max Kellermann 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: fix i_nlink underrun during async unlink

2026-03-25T10:08:33+00:00

commit ce0123cbb4a40a2f1bbb815f292b26e96088639f upstream.

During async unlink, we drop the `i_nlink` counter before we receive
the completion (that will eventually update the `i_nlink`) because "we
assume that the unlink will succeed".  That is not a bad idea, but it
races against deletions by other clients (or against the completion of
our own unlink) and can lead to an underrun which emits a WARNING like
this one:

 WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68
 Modules linked in:
 CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655
 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023
 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : drop_nlink+0x50/0x68
 lr : ceph_unlink+0x6c4/0x720
 sp : ffff80012173bc90
 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680
 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647
 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203
 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365
 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec
 x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74
 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94
 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002
 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000
 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8
 Call trace:
  drop_nlink+0x50/0x68 (P)
  vfs_unlink+0xb0/0x2e8
  do_unlinkat+0x204/0x288
  __arm64_sys_unlinkat+0x3c/0x80
  invoke_syscall.constprop.0+0x54/0xe8
  do_el0_svc+0xa4/0xc8
  el0_svc+0x18/0x58
  el0t_64_sync_handler+0x104/0x130
  el0t_64_sync+0x154/0x158

In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the
CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion.

Meanwhile, between this call and the following drop_nlink() call, a
worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or
just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own
completion).  These will lead to a set_nlink() call, updating the
`i_nlink` counter to the value received from the MDS.  If that new
`i_nlink` value happens to be zero, it is illegal to decrement it
further.  But that is exactly what ceph_unlink() will do then.

The WARNING can be reproduced this way:

1. Force async unlink; only the async code path is affected.  Having
   no real clue about Ceph internals, I was unable to find out why the
   MDS wouldn't give me the "Fxr" capabilities, so I patched
   get_caps_for_async_unlink() to always succeed.

   (Note that the WARNING dump above was found on an unpatched kernel,
   without this kludge - this is not a theoretical bug.)

2. Add a sleep call after ceph_mdsc_submit_request() so the unlink
   completion gets handled by a worker thread before drop_nlink() is
   called.  This guarantees that the `i_nlink` is already zero before
   drop_nlink() runs.

The solution is to skip the counter decrement when it is already zero,
but doing so without a lock is still racy (TOCTOU).  Since
ceph_fill_inode() and handle_cap_grant() both hold the
`ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this
seems like the proper lock to protect the `i_nlink` updates.

I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using
`afs_vnode.cb_lock`).  All three have the zero check as well.

Cc: stable@vger.kernel.org
Fixes: 2ccb45462aea ("ceph: perform asynchronous unlink if we have sufficient caps")
Signed-off-by: Max Kellermann 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: add a bunch of missing ceph_path_info initializers

2026-03-25T10:08:33+00:00

commit 43323a5934b660afae687e8e4e95ac328615a5c4 upstream.

ceph_mdsc_build_path() must be called with a zero-initialized
ceph_path_info parameter, or else the following
ceph_mdsc_free_path_info() may crash.

Example crash (on Linux 6.18.12):

  virt_to_cache: Object is not a Slab page!
  WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6732 kmem_cache_free+0x316/0x400
  [...]
  Call Trace:
   [...]
   ceph_open+0x13d/0x3e0
   do_dentry_open+0x134/0x480
   vfs_open+0x2a/0xe0
   path_openat+0x9a3/0x1160
  [...]
  cache_from_obj: Wrong slab cache. names_cache but object is from ceph_inode_info
  WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6746 kmem_cache_free+0x2dd/0x400
  [...]
  kernel BUG at mm/slub.c:634!
  Oops: invalid opcode: 0000 [#1] SMP NOPTI
  RIP: 0010:__slab_free+0x1a4/0x350

Some of the ceph_mdsc_build_path() callers had initializers, but
others had not, even though they were all added by commit 15f519e9f883
("ceph: fix race condition validating r_parent before applying state").
The ones without initializer are suspectible to random crashes.  (I can
imagine it could even be possible to exploit this bug to elevate
privileges.)

Unfortunately, these Ceph functions are undocumented and its semantics
can only be derived from the code.  I see that ceph_mdsc_build_path()
initializes the structure only on success, but not on error.

Calling ceph_mdsc_free_path_info() after a failed
ceph_mdsc_build_path() call does not even make sense, but that's what
all callers do, and for it to be safe, the structure must be
zero-initialized.  The least intrusive approach to fix this is
therefore to add initializers everywhere.

Cc: stable@vger.kernel.org
Fixes: 15f519e9f883 ("ceph: fix race condition validating r_parent before applying state")
Signed-off-by: Max Kellermann 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: supply snapshot context in ceph_zero_partial_object()

2026-03-04T12:21:54+00:00

[ Upstream commit f16bd3fa74a2084ee7e16a8a2be7e7399b970907 ]

The ceph_zero_partial_object function was missing proper snapshot
context for its OSD write operations, which could lead to data
inconsistencies in snapshots.

Reproducer:
../src/vstart.sh --new -x --localhost --bluestore
./bin/ceph auth caps client.fs_a mds 'allow rwps fsname=a' mon 'allow r fsname=a' osd 'allow rw tag cephfs data=a'
mount -t ceph fs_a@.a=/ /mnt/mycephfs/ -o conf=./ceph.conf
dd if=/dev/urandom of=/mnt/mycephfs/foo bs=64K count=1
mkdir /mnt/mycephfs/.snap/snap1
md5sum /mnt/mycephfs/.snap/snap1/foo
fallocate -p -o 0 -l 4096 /mnt/mycephfs/foo
echo 3 > /proc/sys/vm/drop/caches
md5sum /mnt/mycephfs/.snap/snap1/foo # get different md5sum!!

Cc: stable@vger.kernel.org
Fixes: ad7a60de882ac ("ceph: punch hole support")
Signed-off-by: ethanwu 
Reviewed-by: Viacheslav Dubeyko 
Tested-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Sasha Levin

ceph: supply snapshot context in ceph_uninline_data()

2026-03-04T12:21:27+00:00

[ Upstream commit 305ff6b3a03c230d3c07b61457e961406d979693 ]

The ceph_uninline_data function was missing proper snapshot context
handling for its OSD write operations. Both CEPH_OSD_OP_CREATE and
CEPH_OSD_OP_WRITE requests were passing NULL instead of the appropriate
snapshot context, which could lead to unnecessary object clone.

Reproducer:
../src/vstart.sh --new -x --localhost --bluestore
// turn on cephfs inline data
./bin/ceph fs set a inline_data true --yes-i-really-really-mean-it
// allow fs_a client to take snapshot
./bin/ceph auth caps client.fs_a mds 'allow rwps fsname=a' mon 'allow r fsname=a' osd 'allow rw tag cephfs data=a'
// mount cephfs with fuse, since kernel cephfs doesn't support inline write
ceph-fuse --id fs_a -m 127.0.0.1:40318 --conf ceph.conf -d /mnt/mycephfs/
// bump snapshot seq
mkdir /mnt/mycephfs/.snap/snap1
echo "foo" > /mnt/mycephfs/test
// umount and mount it again using kernel cephfs client
umount /mnt/mycephfs
mount -t ceph fs_a@.a=/ /mnt/mycephfs/ -o conf=./ceph.conf
echo "bar" >> /mnt/mycephfs/test
./bin/rados listsnaps -p cephfs.a.data $(printf "%x\n" $(stat -c %i /mnt/mycephfs/test)).00000000

will see this object does unnecessary clone
1000000000a.00000000 (seq:2):
cloneid snaps   size    overlap
2       2       4       []
head    -       8

but it's expected to see
10000000000.00000000 (seq:2):
cloneid snaps   size    overlap
head    -       8

since there's no snapshot between these 2 writes

clone happened because the first osd request CEPH_OSD_OP_CREATE doesn't
pass snap context so object is created with snap seq 0, but later data
writeback is equipped with snapshot context.
snap.seq(1) > object snap seq(0), so osd does object clone.

This fix properly acquiring the snapshot context before performing
write operations.

Signed-off-by: ethanwu 
Reviewed-by: Viacheslav Dubeyko 
Tested-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Sasha Levin

ceph: fix oops due to invalid pointer for kfree() in parse_longname()

2026-02-11T12:40:17+00:00

commit bc8dedae022ce3058659c3addef3ec4b41d15e00 upstream.

This fixes a kernel oops when reading ceph snapshot directories (.snap),
for example by simply running `ls /mnt/my_ceph/.snap`.

The variable str is guarded by __free(kfree), but advanced by one for
skipping the initial '_' in snapshot names. Thus, kfree() is called
with an invalid pointer.  This patch removes the need for advancing the
pointer so kfree() is called with correct memory pointer.

Steps to reproduce:

1. Create snapshots on a cephfs volume (I've 63 snaps in my testcase)

2. Add cephfs mount to fstab
$ echo "samba-fileserver@.files=/volumes/datapool/stuff/3461082b-ecc9-4e82-8549-3fd2590d3fb6      /mnt/test/stuff   ceph     acl,noatime,_netdev    0       0" >> /etc/fstab

3. Reboot the system
$ systemctl reboot

4. Check if it's really mounted
$ mount | grep stuff

5. List snapshots (expected 63 snapshots on my system)
$ ls /mnt/test/stuff/.snap

Now ls hangs forever and the kernel log shows the oops.

Cc: stable@vger.kernel.org
Fixes: 101841c38346 ("[ceph] parse_longname(): strrchr() expects NUL-terminated string")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220807
Suggested-by: Helge Deller 
Signed-off-by: Daniel Vogelbacher 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: fix NULL pointer dereference in ceph_mds_auth_match()

2026-02-11T12:40:16+00:00

commit 7987cce375ac8ce98e170a77aa2399f2cf6eb99f upstream.

The CephFS kernel client has regression starting from 6.18-rc1.
We have issue in ceph_mds_auth_match() if fs_name == NULL:

    const char fs_name = mdsc->fsc->mount_options->mds_namespace;
    ...
    if (auth->match.fs_name && strcmp(auth->match.fs_name, fs_name)) {
            / fsname mismatch, try next one */
            return 0;
    }

Patrick Donnelly suggested that: In summary, we should definitely start
decoding `fs_name` from the MDSMap and do strict authorizations checks
against it. Note that the `-o mds_namespace=foo` should only be used for
selecting the file system to mount and nothing else. It's possible
no mds_namespace is specified but the kernel will mount the only
file system that exists which may have name "foo".

This patch reworks ceph_mdsmap_decode() and namespace_equals() with
the goal of supporting the suggested concept. Now struct ceph_mdsmap
contains m_fs_name field that receives copy of extracted FS name
by ceph_extract_encoded_string(). For the case of "old" CephFS file
systems, it is used "cephfs" name.

[ idryomov: replace redundant %*pE with %s in ceph_mdsmap_decode(),
  get rid of a series of strlen() calls in ceph_namespace_match(),
  drop changes to namespace_equals() body to avoid treating empty
  mds_namespace as equal, drop changes to ceph_mdsc_handle_fsmap()
  as namespace_equals() isn't an equivalent substitution there ]

Cc: stable@vger.kernel.org
Fixes: 22c73d52a6d0 ("ceph: fix multifs mds auth caps issue")
Link: https://tracker.ceph.com/issues/73886
Signed-off-by: Viacheslav Dubeyko 
Reviewed-by: Patrick Donnelly 
Tested-by: Patrick Donnelly 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: fix multifs mds auth caps issue

2025-11-13T20:34:35+00:00

[ Upstream commit 22c73d52a6d05c5a2053385c0d6cd9984732799d ]

The mds auth caps check should also validate the
fsname along with the associated caps. Not doing
so would result in applying the mds auth caps of
one fs on to the other fs in a multifs ceph cluster.
The bug causes multiple issues w.r.t user
authentication, following is one such example.

Steps to Reproduce (on vstart cluster):
1. Create two file systems in a cluster, say 'fsname1' and 'fsname2'
2. Authorize read only permission to the user 'client.usr' on fs 'fsname1'
    $ceph fs authorize fsname1 client.usr / r
3. Authorize read and write permission to the same user 'client.usr' on fs 'fsname2'
    $ceph fs authorize fsname2 client.usr / rw
4. Update the keyring
    $ceph auth get client.usr >> ./keyring

With above permssions for the user 'client.usr', following is the
expectation.
  a. The 'client.usr' should be able to only read the contents
     and not allowed to create or delete files on file system 'fsname1'.
  b. The 'client.usr' should be able to read/write on file system 'fsname2'.

But, with this bug, the 'client.usr' is allowed to read/write on file
system 'fsname1'. See below.

5. Mount the file system 'fsname1' with the user 'client.usr'
     $sudo bin/mount.ceph usr@.fsname1=/ /kmnt_fsname1_usr/
6. Try creating a file on file system 'fsname1' with user 'client.usr'. This
   should fail but passes with this bug.
     $touch /kmnt_fsname1_usr/file1
7. Mount the file system 'fsname1' with the user 'client.admin' and create a
   file.
     $sudo bin/mount.ceph admin@.fsname1=/ /kmnt_fsname1_admin
     $echo "data" > /kmnt_fsname1_admin/admin_file1
8. Try removing an existing file on file system 'fsname1' with the user
   'client.usr'. This shoudn't succeed but succeeds with the bug.
     $rm -f /kmnt_fsname1_usr/admin_file1

For more information, please take a look at the corresponding mds/fuse patch
and tests added by looking into the tracker mentioned below.

v2: Fix a possible null dereference in doutc
v3: Don't store fsname from mdsmap, validate against
    ceph_mount_options's fsname and use it
v4: Code refactor, better warning message and
    fix possible compiler warning

[ Slava.Dubeyko: "fsname check failed" -> "fsname mismatch" ]

Link: https://tracker.ceph.com/issues/72167
Signed-off-by: Kotresh HR 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Sasha Levin

ceph: refactor wake_up_bit() pattern of calling

2025-11-13T20:34:35+00:00

[ Upstream commit 53db6f25ee47cb1265141d31562604e56146919a ]

The wake_up_bit() is called in ceph_async_unlink_cb(),
wake_async_create_waiters(), and ceph_finish_async_create().
It makes sense to switch on clear_bit() function, because
it makes the code much cleaner and easier to understand.
More important rework is the adding of smp_mb__after_atomic()
memory barrier after the bit modification and before
wake_up_bit() call. It can prevent potential race condition
of accessing the modified bit in other threads. Luckily,
clear_and_wake_up_bit() already implements the required
functionality pattern:

static inline void clear_and_wake_up_bit(int bit, unsigned long *word)
{
	clear_bit_unlock(bit, word);
	/* See wake_up_bit() for which memory barrier you need to use. */
	smp_mb__after_atomic();
	wake_up_bit(word, bit);
}

Signed-off-by: Viacheslav Dubeyko 
Reviewed-by: Alex Markuze 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Sasha Levin

ceph: fix potential race condition in ceph_ioctl_lazyio()

2025-11-13T20:34:35+00:00

[ Upstream commit 5824ccba9a39a3ad914fc9b2972a2c1119abaac9 ]

The Coverity Scan service has detected potential
race condition in ceph_ioctl_lazyio() [1].

The CID 1591046 contains explanation: "Check of thread-shared
field evades lock acquisition (LOCK_EVASION). Thread1 sets
fmode to a new value. Now the two threads have an inconsistent
view of fmode and updates to fields correlated with fmode
may be lost. The data guarded by this critical section may
be read while in an inconsistent state or modified by multiple
racing threads. In ceph_ioctl_lazyio: Checking the value of
a thread-shared field outside of a locked region to determine
if a locked operation involving that thread shared field
has completed. (CWE-543)".

The patch places fi->fmode field access under ci->i_ceph_lock
protection. Also, it introduces the is_file_already_lazy
variable that is set under the lock and it is checked later
out of scope of critical section.

[1] https://scan5.scan.coverity.com/#/project-view/64304/10063?selectedIssue=1591046

Signed-off-by: Viacheslav Dubeyko 
Reviewed-by: Alex Markuze 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Sasha Levin