In the Linux kernel, the following vulnerability has been resolved:
ceph: fix memory leak in ceph_mds_auth_match()
We now free the temporary target path substring allocation on every
possible branch, instead of omitting the default branch.  In some
cases, a memory leak occured, which could rapidly crash the system
(depending on how many file accesses were attempted).
This was detected in production because it caused a continuous memory
growth, eventually triggering kernel OOM and completely hard-locking
the kernel.
Relevant kmemleak stacktrace:
    unreferenced object 0xffff888131e69900 (size 128):
      comm "git", pid 66104, jiffies 4295435999
      hex dump (first 32 bytes):
        76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65  volumes/containe
        72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67  rs/gitea/gitea/g
      backtrace (crc 2f3bb450):
        [<ffffffffaa68fb49>] __kmalloc_noprof+0x359/0x510
        [<ffffffffc32bf1df>] ceph_mds_check_access+0x5bf/0x14e0 [ceph]
        [<ffffffffc3235722>] ceph_open+0x312/0xd80 [ceph]
        [<ffffffffaa7dd786>] do_dentry_open+0x456/0x1120
        [<ffffffffaa7e3729>] vfs_open+0x79/0x360
        [<ffffffffaa832875>] path_openat+0x1de5/0x4390
        [<ffffffffaa834fcc>] do_filp_open+0x19c/0x3c0
        [<ffffffffaa7e44a1>] do_sys_openat2+0x141/0x180
        [<ffffffffaa7e4945>] __x64_sys_open+0xe5/0x1a0
        [<ffffffffac2cc2f7>] do_syscall_64+0xb7/0x210
        [<ffffffffac400130>] entry_SYSCALL_64_after_hwframe+0x77/0x7f
It can be triggered by mouting a subdirectory of a CephFS filesystem,
and then trying to access files on this subdirectory with an auth token
using a path-scoped capability:
    $ ceph auth get client.services
    [client.services]
            key = REDACTED
            caps mds = "allow rw fsname=cephfs path=/volumes/"
            caps mon = "allow r fsname=cephfs"
            caps osd = "allow rw tag cephfs data=cephfs"
    $ cat /proc/self/mounts
    services@[REDACTED].cephfs=/volumes/containers /ceph/containers ceph rw,noatime,name=services,secret=<hidden>,ms_mode=prefer-crc,mount_timeout=300,acl,mon_addr=[REDACTED]:3300,recover_session=clean 0 0
    $ seq 1 1000000 | xargs -P32 --replace={} touch /ceph/containers/file-{} && \
    seq 1 1000000 | xargs -P32 --replace={} cat /ceph/containers/file-{}
[ idryomov: combine if statements, rename rc to path_matched and make
            it a bool, formatting ]
                
            Metrics
Affected Vendors & Products
References
        History
                    Wed, 01 Oct 2025 20:15:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| Metrics | 
        
        ssvc
         
  | 
Thu, 06 Mar 2025 12:45:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| First Time appeared | 
        
        Linux
         Linux linux Kernel  | 
|
| Weaknesses | CWE-401 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products | 
        
        Linux
         Linux linux Kernel  | 
Fri, 28 Feb 2025 02:00:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| References | 
         | |
| Metrics | 
        
        
        threat_severity
         
  | 
    
        
        cvssV3_1
         
 
  | 
Thu, 27 Feb 2025 02:45:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ceph: fix memory leak in ceph_mds_auth_match() We now free the temporary target path substring allocation on every possible branch, instead of omitting the default branch. In some cases, a memory leak occured, which could rapidly crash the system (depending on how many file accesses were attempted). This was detected in production because it caused a continuous memory growth, eventually triggering kernel OOM and completely hard-locking the kernel. Relevant kmemleak stacktrace: unreferenced object 0xffff888131e69900 (size 128): comm "git", pid 66104, jiffies 4295435999 hex dump (first 32 bytes): 76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65 volumes/containe 72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67 rs/gitea/gitea/g backtrace (crc 2f3bb450): [<ffffffffaa68fb49>] __kmalloc_noprof+0x359/0x510 [<ffffffffc32bf1df>] ceph_mds_check_access+0x5bf/0x14e0 [ceph] [<ffffffffc3235722>] ceph_open+0x312/0xd80 [ceph] [<ffffffffaa7dd786>] do_dentry_open+0x456/0x1120 [<ffffffffaa7e3729>] vfs_open+0x79/0x360 [<ffffffffaa832875>] path_openat+0x1de5/0x4390 [<ffffffffaa834fcc>] do_filp_open+0x19c/0x3c0 [<ffffffffaa7e44a1>] do_sys_openat2+0x141/0x180 [<ffffffffaa7e4945>] __x64_sys_open+0xe5/0x1a0 [<ffffffffac2cc2f7>] do_syscall_64+0xb7/0x210 [<ffffffffac400130>] entry_SYSCALL_64_after_hwframe+0x77/0x7f It can be triggered by mouting a subdirectory of a CephFS filesystem, and then trying to access files on this subdirectory with an auth token using a path-scoped capability: $ ceph auth get client.services [client.services] key = REDACTED caps mds = "allow rw fsname=cephfs path=/volumes/" caps mon = "allow r fsname=cephfs" caps osd = "allow rw tag cephfs data=cephfs" $ cat /proc/self/mounts services@[REDACTED].cephfs=/volumes/containers /ceph/containers ceph rw,noatime,name=services,secret=<hidden>,ms_mode=prefer-crc,mount_timeout=300,acl,mon_addr=[REDACTED]:3300,recover_session=clean 0 0 $ seq 1 1000000 | xargs -P32 --replace={} touch /ceph/containers/file-{} && \ seq 1 1000000 | xargs -P32 --replace={} cat /ceph/containers/file-{} [ idryomov: combine if statements, rename rc to path_matched and make it a bool, formatting ] | |
| Title | ceph: fix memory leak in ceph_mds_auth_match() | |
| References | 
         | 
Status: PUBLISHED
Assigner: Linux
Published: 2025-02-27T02:12:13.434Z
Updated: 2025-10-01T19:36:42.012Z
Reserved: 2024-12-29T08:45:45.756Z
Link: CVE-2025-21737
Updated: 2025-10-01T16:55:31.336Z
Status : Modified
Published: 2025-02-27T03:15:14.327
Modified: 2025-10-01T20:18:22.513
Link: CVE-2025-21737