Описание
In the Linux kernel, the following vulnerability has been resolved:
smb: Don't leak cfid when reconnect races with open_cached_dir
open_cached_dir() may either race with the tcon reconnection even before
compound_send_recv() or directly trigger a reconnection via
SMB2_open_init() or SMB_query_info_init().
The reconnection process invokes invalidate_all_cached_dirs() via
cifs_mark_open_files_invalid(), which removes all cfids from the
cfids->entries list but doesn't drop a ref if has_lease isn't true. This
results in the currently-being-constructed cfid not being on the list,
but still having a refcount of 2. It leaks if returned from
open_cached_dir().
Fix this by setting cfid->has_lease when the ref is actually taken; the
cfid will not be used by other threads until it has a valid time.
Addresses these kmemleaks:
unreferenced object 0xffff8881090c4000 (size 1024):
comm "bash", pid 1860, jiffies 4295126592
hex dump (first 32 bytes):
00 01 00 00 00 00 ad de 22 01 00 00 00 00 ad de ........".......
00 ca 45 22 81 88 ff ff f8 dc 4f 04 81 88 ff ff ..E"......O.....
backtrace (crc 6f58c20f):
[] __kmalloc_cache_noprof+0x2be/0x350
[] open_cached_dir+0x993/0x1fb0
[] cifs_readdir+0x15a0/0x1d50
[] iterate_dir+0x28f/0x4b0
[] __x64_sys_getdents64+0xfd/0x200
[] do_syscall_64+0x95/0x1a0
[] entry_SYSCALL_64_after_hwframe+0x76/0x7e
unreferenced object 0xffff8881044fdcf8 (size 8):
comm "bash", pid 1860, jiffies 4295126592
hex dump (first 8 bytes):
00 cc cc cc cc cc cc cc ........
backtrace (crc 10c106a9):
[] __kmalloc_node_track_caller_noprof+0x363/0x480
[] kstrdup+0x36/0x60
[] open_cached_dir+0x9b0/0x1fb0
[] cifs_readdir+0x15a0/0x1d50
[] iterate_dir+0x28f/0x4b0
[] __x64_sys_getdents64+0xfd/0x200
[] do_syscall_64+0x95/0x1a0
[] entry_SYSCALL_64_after_hwframe+0x76/0x7e
And addresses these BUG splats when unmounting the SMB filesystem:
BUG: Dentry ffff888140590ba0{i=1000000000080,n=/} still in use (2) [unmount of cifs cifs]
WARNING: CPU: 3 PID: 3433 at fs/dcache.c:1536 umount_check+0xd0/0x100
Modules linked in:
CPU: 3 UID: 0 PID: 3433 Comm: bash Not tainted 6.12.0-rc4-g850925a8133c-dirty #49
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
RIP: 0010:umount_check+0xd0/0x100
Code: 8d 7c 24 40 e8 31 5a f4 ff 49 8b 54 24 40 41 56 49 89 e9 45 89 e8 48 89 d9 41 57 48 89 de 48 c7 c7 80 e7 db ac e8 f0 72 9a ff <0f> 0b 58 31 c0 5a 5b 5d 41 5c 41 5d 41 5e 41 5f e9 2b e5 5d 01 41
RSP: 0018:ffff88811cc27978 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff888140590ba0 RCX: ffffffffaaf20bae
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff8881f6fb6f40
RBP: ffff8881462ec000 R08: 0000000000000001 R09: ffffed1023984ee3
R10: ffff88811cc2771f R11: 00000000016cfcc0 R12: ffff888134383e08
R13: 0000000000000002 R14: ffff8881462ec668 R15: ffffffffaceab4c0
FS: 00007f23bfa98740(0000) GS:ffff8881f6f80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556de4a6f808 CR3: 0000000123c80000 CR4: 0000000000350ef0
Call Trace:
d_walk+0x6a/0x530
shrink_dcache_for_umount+0x6a/0x200
generic_shutdown_super+0x52/0x2a0
kill_anon_super+0x22/0x40
cifs_kill_sb+0x159/0x1e0
deactivate_locked_super+0x66/0xe0
cleanup_mnt+0x140/0x210
task_work_run+0xfb/0x170
syscall_exit_to_user_mode+0x29f/0x2b0
do_syscall_64+0xa1/0x1a0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f23bfb93ae7
Code: ff ff ff ff c3 66 0f 1f 44 00 00 48 8b 0d 11 93 0d 00 f7 d8 64 89 01 b8 ff ff ff ff eb bf 0f 1f 44 00 00 b8 50 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e9 92 0d 00 f7 d8 64 89
---truncated---
A flaw was found in the Linux kernel's Server Message Block (SMB) client subsystem. A race condition can occur when an SMB reconnection event takes place while opening a cached directory, resulting in improperly handled reference counts and memory leaks. A local user could exploit this vulnerability through concurrent file operations during connection resets, leading to a system crash and a Denial of Service (DoS).
Меры по смягчению последствий
To mitigate this vulnerability, prevent the cifs kernel module from loading if SMB/CIFS network mounts are not required in your environment:
- Create a configuration file to prevent the module from being loaded:
echo "install cifs /bin/true" >> /etc/modprobe.d/disable-cifs.conf
- If the module is already loaded, ensure all SMB/CIFS shares are unmounted, then unload the module:
modprobe -r cifs
Caveats: Applying this mitigation disables the ability to mount SMB/CIFS network file systems. If the CIFS module cannot be safely unloaded due to active mounts or dependencies, a system reboot is required for the configuration to take effect.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Affected |
Показывать по
Дополнительная информация
Статус:
6.3 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: smb: Don't leak cfid when reconnect races with open_cached_dir open_cached_dir() may either race with the tcon reconnection even before compound_send_recv() or directly trigger a reconnection via SMB2_open_init() or SMB_query_info_init(). The reconnection process invokes invalidate_all_cached_dirs() via cifs_mark_open_files_invalid(), which removes all cfids from the cfids->entries list but doesn't drop a ref if has_lease isn't true. This results in the currently-being-constructed cfid not being on the list, but still having a refcount of 2. It leaks if returned from open_cached_dir(). Fix this by setting cfid->has_lease when the ref is actually taken; the cfid will not be used by other threads until it has a valid time. Addresses these kmemleaks: unreferenced object 0xffff8881090c4000 (size 1024): comm "bash", pid 1860, jiffies 4295126592 hex dump (first 32 bytes): 00 01 00 00 00 00 ad de 22 01 00 00 00 00 ad de ....
In the Linux kernel, the following vulnerability has been resolved: smb: Don't leak cfid when reconnect races with open_cached_dir open_cached_dir() may either race with the tcon reconnection even before compound_send_recv() or directly trigger a reconnection via SMB2_open_init() or SMB_query_info_init(). The reconnection process invokes invalidate_all_cached_dirs() via cifs_mark_open_files_invalid(), which removes all cfids from the cfids->entries list but doesn't drop a ref if has_lease isn't true. This results in the currently-being-constructed cfid not being on the list, but still having a refcount of 2. It leaks if returned from open_cached_dir(). Fix this by setting cfid->has_lease when the ref is actually taken; the cfid will not be used by other threads until it has a valid time. Addresses these kmemleaks: unreferenced object 0xffff8881090c4000 (size 1024): comm "bash", pid 1860, jiffies 4295126592 hex dump (first 32 bytes): 00 01 00 00 00 00 ad de 22 01 00 00 00
In the Linux kernel, the following vulnerability has been resolved: s ...
In the Linux kernel, the following vulnerability has been resolved: smb: Don't leak cfid when reconnect races with open_cached_dir open_cached_dir() may either race with the tcon reconnection even before compound_send_recv() or directly trigger a reconnection via SMB2_open_init() or SMB_query_info_init(). The reconnection process invokes invalidate_all_cached_dirs() via cifs_mark_open_files_invalid(), which removes all cfids from the cfids->entries list but doesn't drop a ref if has_lease isn't true. This results in the currently-being-constructed cfid not being on the list, but still having a refcount of 2. It leaks if returned from open_cached_dir(). Fix this by setting cfid->has_lease when the ref is actually taken; the cfid will not be used by other threads until it has a valid time. Addresses these kmemleaks: unreferenced object 0xffff8881090c4000 (size 1024): comm "bash", pid 1860, jiffies 4295126592 hex dump (first 32 bytes): 00 01 00 00 00 00 ad de 22 01 00 00 ...
Уязвимость модуля fs/smb/client/cached_dir.c ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
6.3 Medium
CVSS3