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Message-ID: <2025010812-CVE-2024-56779-74f5@gregkh>
Date: Wed, 8 Jan 2025 18:49:17 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56779: nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur
Description
===========
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>
dump_stack_lvl+0x53/0x70
slab_err+0xb0/0xf0
__kmem_cache_shutdown+0x15c/0x310
kmem_cache_destroy+0x66/0x160
nfsd_file_cache_shutdown+0xac/0x210 [nfsd]
nfsd_destroy_serv+0x251/0x2a0 [nfsd]
nfsd_svc+0x125/0x1e0 [nfsd]
write_threads+0x16a/0x2a0 [nfsd]
nfsctl_transaction_write+0x74/0xa0 [nfsd]
vfs_write+0x1ae/0x6d0
ksys_write+0xc1/0x160
do_syscall_64+0x5f/0x170
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Disabling lock debugging due to kernel taint
Object 0xff11000110e2ac38 @offset=3128
Allocated in nfsd_file_do_acquire+0x20f/0xa30 [nfsd] age=1635 cpu=3
pid=800
nfsd_file_do_acquire+0x20f/0xa30 [nfsd]
nfsd_file_acquire_opened+0x5f/0x90 [nfsd]
nfs4_get_vfs_file+0x4c9/0x570 [nfsd]
nfsd4_process_open2+0x713/0x1070 [nfsd]
nfsd4_open+0x74b/0x8b0 [nfsd]
nfsd4_proc_compound+0x70b/0xc20 [nfsd]
nfsd_dispatch+0x1b4/0x3a0 [nfsd]
svc_process_common+0x5b8/0xc50 [sunrpc]
svc_process+0x2ab/0x3b0 [sunrpc]
svc_handle_xprt+0x681/0xa20 [sunrpc]
nfsd+0x183/0x220 [nfsd]
kthread+0x199/0x1e0
ret_from_fork+0x31/0x60
ret_from_fork_asm+0x1a/0x30
Add nfs4_openowner_unhashed to help found unhashed nfs4_openowner, and
break nfsd4_open process to fix this problem.
The Linux kernel CVE team has assigned CVE-2024-56779 to this issue.
Affected and fixed versions
===========================
Fixed in 5.4.287 with commit a85364f0d30dee01c5d5b4afa55a9629a8f36d8e
Fixed in 5.10.231 with commit 2d505a801e57428057563762f67a5a62009b2600
Fixed in 5.15.174 with commit 0ab0a3ad24e970e894abcac58f85c332d1726749
Fixed in 6.1.120 with commit 45abb68c941ebc9a35c6d3a7b08196712093c636
Fixed in 6.6.64 with commit 37dfc81266d3a32294524bfadd3396614f8633ee
Fixed in 6.12.4 with commit 6f73f920b7ad0084373e46121d7ac34117aed652
Fixed in 6.13-rc1 with commit 98100e88dd8865999dc6379a3356cd799795fe7b
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2024-56779
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
fs/nfsd/nfs4state.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/a85364f0d30dee01c5d5b4afa55a9629a8f36d8e
https://git.kernel.org/stable/c/2d505a801e57428057563762f67a5a62009b2600
https://git.kernel.org/stable/c/0ab0a3ad24e970e894abcac58f85c332d1726749
https://git.kernel.org/stable/c/45abb68c941ebc9a35c6d3a7b08196712093c636
https://git.kernel.org/stable/c/37dfc81266d3a32294524bfadd3396614f8633ee
https://git.kernel.org/stable/c/6f73f920b7ad0084373e46121d7ac34117aed652
https://git.kernel.org/stable/c/98100e88dd8865999dc6379a3356cd799795fe7b
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