In the Linux kernel, the following vulnerability has been resolved:
nbd: call genl_unregister_family() first in nbd_cleanup()
Otherwise there may be race between module removal and the handling of
netlink command, which can lead to the oops as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000098
Oops: 0002 [#1] SMP PTI
CPU: 1 PID: 31299 Comm: nbd-client Tainted: G E 5.14.0-rc4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:down_write+0x1a/0x50
Call Trace:
start_creating+0x89/0x130
debugfs_create_dir+0x1b/0x130
nbd_start_device+0x13d/0x390 [nbd]
nbd_genl_connect+0x42f/0x748 [nbd]
genl_family_rcv_msg_doit.isra.0+0xec/0x150
genl_rcv_msg+0xe5/0x1e0
netlink_rcv_skb+0x55/0x100
genl_rcv+0x29/0x40
netlink_unicast+0x1a8/0x250
netlink_sendmsg+0x21b/0x430
____sys_sendmsg+0x2a4/0x2d0
___sys_sendmsg+0x81/0xc0
__sys_sendmsg+0x62/0xb0
__x64_sys_sendmsg+0x1f/0x30
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
Modules linked in: nbd(E-)
In the Linux kernel, the following vulnerability has been resolved:
nbd: fix io hung while disconnecting device
In our tests, "qemu-nbd" triggers a io hung:
INFO: task qemu-nbd:11445 blocked for more than 368 seconds.
Not tainted 5.18.0-rc3-next-20220422-00003-g2176915513ca #884
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:qemu-nbd state:D stack: 0 pid:11445 ppid: 1 flags:0x00000000
Call Trace:
<TASK>
__schedule+0x480/0x1050
? _raw_spin_lock_irqsave+0x3e/0xb0
schedule+0x9c/0x1b0
blk_mq_freeze_queue_wait+0x9d/0xf0
? ipi_rseq+0x70/0x70
blk_mq_freeze_queue+0x2b/0x40
nbd_add_socket+0x6b/0x270 [nbd]
nbd_ioctl+0x383/0x510 [nbd]
blkdev_ioctl+0x18e/0x3e0
__x64_sys_ioctl+0xac/0x120
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd8ff706577
RSP: 002b:00007fd8fcdfebf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000040000000 RCX: 00007fd8ff706577
RDX: 000000000000000d RSI: 000000000000ab00 RDI: 000000000000000f
RBP: 000000000000000f R08: 000000000000fbe8 R09: 000055fe497c62b0
R10: 00000002aff20000 R11: 0000000000000246 R12: 000000000000006d
R13: 0000000000000000 R14: 00007ffe82dc5e70 R15: 00007fd8fcdff9c0
"qemu-ndb -d" will call ioctl 'NBD_DISCONNECT' first, however, following
message was found:
block nbd0: Send disconnect failed -32
Which indicate that something is wrong with the server. Then,
"qemu-nbd -d" will call ioctl 'NBD_CLEAR_SOCK', however ioctl can't clear
requests after commit 2516ab1543fd("nbd: only clear the queue on device
teardown"). And in the meantime, request can't complete through timeout
because nbd_xmit_timeout() will always return 'BLK_EH_RESET_TIMER', which
means such request will never be completed in this situation.
Now that the flag 'NBD_CMD_INFLIGHT' can make sure requests won't
complete multiple times, switch back to call nbd_clear_sock() in
nbd_clear_sock_ioctl(), so that inflight requests can be cleared.
In the Linux kernel, the following vulnerability has been resolved:
nbd: fix race between nbd_alloc_config() and module removal
When nbd module is being removing, nbd_alloc_config() may be
called concurrently by nbd_genl_connect(), although try_module_get()
will return false, but nbd_alloc_config() doesn't handle it.
The race may lead to the leak of nbd_config and its related
resources (e.g, recv_workq) and oops in nbd_read_stat() due
to the unload of nbd module as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000040
Oops: 0000 [#1] SMP PTI
CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: knbd16-recv recv_work [nbd]
RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd]
Call Trace:
recv_work+0x3b/0xb0 [nbd]
process_one_work+0x1ed/0x390
worker_thread+0x4a/0x3d0
kthread+0x12a/0x150
ret_from_fork+0x22/0x30
Fixing it by checking the return value of try_module_get()
in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV),
assign nbd->config only when nbd_alloc_config() succeeds to ensure
the value of nbd->config is binary (valid or NULL).
Also adding a debug message to check the reference counter
of nbd_config during module removal.
In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Fix races among concurrent prealloc proc writes
We have no protection against concurrent PCM buffer preallocation
changes via proc files, and it may potentially lead to UAF or some
weird problem. This patch applies the PCM open_mutex to the proc
write operation for avoiding the racy proc writes and the PCM stream
open (and further operations).
In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Fix races among concurrent hw_params and hw_free calls
Currently we have neither proper check nor protection against the
concurrent calls of PCM hw_params and hw_free ioctls, which may result
in a UAF. Since the existing PCM stream lock can't be used for
protecting the whole ioctl operations, we need a new mutex to protect
those racy calls.
This patch introduced a new mutex, runtime->buffer_mutex, and applies
it to both hw_params and hw_free ioctl code paths. Along with it, the
both functions are slightly modified (the mmap_count check is moved
into the state-check block) for code simplicity.
In the Linux kernel, the following vulnerability has been resolved:
NFSD: prevent integer overflow on 32 bit systems
On a 32 bit system, the "len * sizeof(*p)" operation can have an
integer overflow.
In the Linux kernel, the following vulnerability has been resolved:
NFSD: prevent underflow in nfssvc_decode_writeargs()
Smatch complains:
fs/nfsd/nfsxdr.c:341 nfssvc_decode_writeargs()
warn: no lower bound on 'args->len'
Change the type to unsigned to prevent this issue.