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Memory Leak Affecting kernel-debug-devel package, versions *

Severity

 Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (13th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELDEBUGDEVEL-8613767
  • published10 Jan 2025
  • disclosed8 Jan 2025
Report a new vulnerability Found a mistake?

Introduced: 8 Jan 2025

NewCVE-2024-56779  (opens in a new tab)
CWE-401  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-debug-devel.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debug-devel package and not the kernel-debug-devel package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur

The action force umount(umount -f) will attempt to kill all rpc_task even umount operation may ultimately fail if some files remain open. Consequently, if an action attempts to open a file, it can potentially send two rpc_task to nfs server.

               NFS CLIENT

thread1 thread2 open("file") ... nfs4_do_open _nfs4_do_open _nfs4_open_and_get_state _nfs4_proc_open nfs4_run_open_task /* rpc_task1 */ rpc_run_task rpc_wait_for_completion_task

                                umount -f
                                nfs_umount_begin
                                 rpc_killall_tasks
                                  rpc_signal_task
 rpc_task1 been wakeup
 and return -512

_nfs4_do_open // while loop ... nfs4_run_open_task /* rpc_task2 */ rpc_run_task rpc_wait_for_completion_task

While processing an open request, nfsd will first attempt to find or allocate an nfs4_openowner. If it finds an nfs4_openowner that is not marked as NFS4_OO_CONFIRMED, this nfs4_openowner will released. Since two rpc_task can attempt to open the same file simultaneously from the client to server, and because two instances of nfsd can run concurrently, this situation can lead to lots of memory leak. Additionally, when we echo 0 to /proc/fs/nfsd/threads, warning will be triggered.

                NFS SERVER

nfsd1 nfsd2 echo 0 > /proc/fs/nfsd/threads

nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // alloc oo1, stateid1 nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // find oo1, without NFS4_OO_CONFIRMED release_openowner unhash_openowner_locked list_del_init(&oo->oo_perclient) // cannot find this oo // from client, LEAK!!! alloc_stateowner // alloc oo2

nfsd4_process_open2 init_open_stateid // associate oo1 // with stateid1, stateid1 LEAK!!! nfs4_get_vfs_file // alloc nfsd_file1 and nfsd_file_mark1 // all LEAK!!!

                     nfsd4_process_open2
                     ...


                            write_threads
                             ...
                             nfsd_destroy_serv
                              nfsd_shutdown_net
                               nfs4_state_shutdown_net
                                nfs4_state_destroy_net
                                 destroy_client
                                  __destroy_client
                                  // won't find oo1!!!
                             nfsd_shutdown_generic
                              nfsd_file_cache_shutdown
                               kmem_cache_destroy
                               for nfsd_file_slab
                               and nfsd_file_mark_slab
                               // bark since nfsd_file1
                               // and nfsd_file_mark1
                               // still alive

======================================================================= BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on __kmem_cache_shutdown()

Slab 0xffd4000004438a80 objects=34 used=1 fp=0xff11000110e2ad28 flags=0x17ffffc0000240(workingset|head|node=0|zone=2|lastcpupid=0x1fffff) CPU: 4 UID: 0 PID: 757 Comm: sh Not tainted 6.12.0-rc6+ #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dum ---truncated---

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