Linux: >> Linux Kernel >> 4.19.45 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop
A race condition between gether_disconnect() and eth_stop() leads to a
NULL pointer dereference. Specifically, if eth_stop() is triggered
concurrently while gether_disconnect() is tearing down the endpoints,
eth_stop() attempts to access the cleared endpoint descriptor, causing
the following NPE:
Unable to handle kernel NULL pointer dereference
Call trace:
__dwc3_gadget_ep_enable+0x60/0x788
dwc3_gadget_ep_enable+0x70/0xe4
usb_ep_enable+0x60/0x15c
eth_stop+0xb8/0x108
Because eth_stop() crashes while holding the dev->lock, the thread
running gether_disconnect() fails to acquire the same lock and spins
forever, resulting in a hardlockup:
Core - Debugging Information for Hardlockup core(7)
Call trace:
queued_spin_lock_slowpath+0x94/0x488
_raw_spin_lock+0x64/0x6c
gether_disconnect+0x19c/0x1e8
ncm_set_alt+0x68/0x1a0
composite_setup+0x6a0/0xc50
The root cause is that the clearing of dev->port_usb in
gether_disconnect() is delayed until the end of the function.
Move the clearing of dev->port_usb to the very beginning of
gether_disconnect() while holding dev->lock. This cuts off the link
immediately, ensuring eth_stop() will see dev->port_usb as NULL and
safely bail out.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_uac1_legacy: validate control request size
f_audio_complete() copies req->length bytes into a 4-byte stack
variable:
u32 data = 0;
memcpy(&data, req->buf, req->length);
req->length is derived from the host-controlled USB request path,
which can lead to a stack out-of-bounds write.
Validate req->actual against the expected payload size for the
supported control selectors and decode only the expected amount
of data.
This avoids copying a host-influenced length into a fixed-size
stack object.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_hid: move list and spinlock inits from bind to alloc
There was an issue when you did the following:
- setup and bind an hid gadget
- open /dev/hidg0
- use the resulting fd in EPOLL_CTL_ADD
- unbind the UDC
- bind the UDC
- use the fd in EPOLL_CTL_DEL
When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported
within remove_wait_queue (via ep_remove_wait_queue). After some
debugging I found out that the queues, which f_hid registers via
poll_wait were the problem. These were initialized using
init_waitqueue_head inside hidg_bind. So effectively, the bind function
re-initialized the queues while there were still items in them.
The solution is to move the initialization from hidg_bind to hidg_alloc
to extend their lifetimes to the lifetime of the function instance.
Additionally, I found many other possibly problematic init calls in the
bind function, which I moved as well.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_rndis: Fix net_device lifecycle with device_move
The net_device is allocated during function instance creation and
registered during the bind phase with the gadget device as its sysfs
parent. When the function unbinds, the parent device is destroyed, but
the net_device survives, resulting in dangling sysfs symlinks:
console:/ # ls -l /sys/class/net/usb0
lrwxrwxrwx ... /sys/class/net/usb0 ->
/sys/devices/platform/.../gadget.0/net/usb0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0
ls: .../gadget.0/net/usb0: No such file or directory
Use device_move() to reparent the net_device between the gadget device
tree and /sys/devices/virtual across bind and unbind cycles. During the
final unbind, calling device_move(NULL) moves the net_device to the
virtual device tree before the gadget device is destroyed. On rebinding,
device_move() reparents the device back under the new gadget, ensuring
proper sysfs topology and power management ordering.
To maintain compatibility with legacy composite drivers (e.g., multi.c),
the borrowed_net flag is used to indicate whether the network device is
shared and pre-registered during the legacy driver's bind phase.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_subset: Fix net_device lifecycle with device_move
The net_device is allocated during function instance creation and
registered during the bind phase with the gadget device as its sysfs
parent. When the function unbinds, the parent device is destroyed, but
the net_device survives, resulting in dangling sysfs symlinks:
console:/ # ls -l /sys/class/net/usb0
lrwxrwxrwx ... /sys/class/net/usb0 ->
/sys/devices/platform/.../gadget.0/net/usb0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0
ls: .../gadget.0/net/usb0: No such file or directory
Use device_move() to reparent the net_device between the gadget device
tree and /sys/devices/virtual across bind and unbind cycles. During the
final unbind, calling device_move(NULL) moves the net_device to the
virtual device tree before the gadget device is destroyed. On rebinding,
device_move() reparents the device back under the new gadget, ensuring
proper sysfs topology and power management ordering.
To maintain compatibility with legacy composite drivers (e.g., multi.c),
the bound flag is used to indicate whether the network device is shared
and pre-registered during the legacy driver's bind phase.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_eem: Fix net_device lifecycle with device_move
The net_device is allocated during function instance creation and
registered during the bind phase with the gadget device as its sysfs
parent. When the function unbinds, the parent device is destroyed, but
the net_device survives, resulting in dangling sysfs symlinks:
console:/ # ls -l /sys/class/net/usb0
lrwxrwxrwx ... /sys/class/net/usb0 ->
/sys/devices/platform/.../gadget.0/net/usb0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0
ls: .../gadget.0/net/usb0: No such file or directory
Use device_move() to reparent the net_device between the gadget device
tree and /sys/devices/virtual across bind and unbind cycles. During the
final unbind, calling device_move(NULL) moves the net_device to the
virtual device tree before the gadget device is destroyed. On rebinding,
device_move() reparents the device back under the new gadget, ensuring
proper sysfs topology and power management ordering.
To maintain compatibility with legacy composite drivers (e.g., multi.c),
the bound flag is used to indicate whether the network device is shared
and pre-registered during the legacy driver's bind phase.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_ecm: Fix net_device lifecycle with device_move
The net_device is allocated during function instance creation and
registered during the bind phase with the gadget device as its sysfs
parent. When the function unbinds, the parent device is destroyed, but
the net_device survives, resulting in dangling sysfs symlinks:
console:/ # ls -l /sys/class/net/usb0
lrwxrwxrwx ... /sys/class/net/usb0 ->
/sys/devices/platform/.../gadget.0/net/usb0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0
ls: .../gadget.0/net/usb0: No such file or directory
Use device_move() to reparent the net_device between the gadget device
tree and /sys/devices/virtual across bind and unbind cycles. During the
final unbind, calling device_move(NULL) moves the net_device to the
virtual device tree before the gadget device is destroyed. On rebinding,
device_move() reparents the device back under the new gadget, ensuring
proper sysfs topology and power management ordering.
To maintain compatibility with legacy composite drivers (e.g., multi.c),
the bound flag is used to indicate whether the network device is shared
and pre-registered during the legacy driver's bind phase.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()
The xfstests case "generic/107" and syzbot have both reported a NULL
pointer dereference.
The concurrent scenario that triggers the panic is as follows:
F2FS_WB_CP_DATA write callback umount
- f2fs_write_checkpoint
- f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA)
- blk_mq_end_request
- bio_endio
- f2fs_write_end_io
: dec_page_count(sbi, F2FS_WB_CP_DATA)
: wake_up(&sbi->cp_wait)
- kill_f2fs_super
- kill_block_super
- f2fs_put_super
: iput(sbi->node_inode)
: sbi->node_inode = NULL
: f2fs_in_warm_node_list
- is_node_folio // sbi->node_inode is NULL and panic
The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and
sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is
decremented to zero. As a result, f2fs_in_warm_node_list() may
dereference a NULL node_inode when checking whether a folio belongs to
the node inode, leading to a panic.
This patch fixes the issue by calling f2fs_in_warm_node_list() before
decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the
use-after-free condition.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix missing validation of ticket length in non-XDR key preparsing
In rxrpc_preparse(), there are two paths for parsing key payloads: the
XDR path (for large payloads) and the non-XDR path (for payloads <= 28
bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly
validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR
path fails to do so.
This allows an unprivileged user to provide a very large ticket length.
When this key is later read via rxrpc_read(), the total
token size (toksize) calculation results in a value that exceeds
AFSTOKEN_LENGTH_MAX, triggering a WARN_ON().
[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]
Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse()
to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX,
bringing it into parity with the XDR parsing logic.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
crypto: ccp: Don't attempt to copy PDH cert to userspace if PSP command failed
When retrieving the PDH cert, don't attempt to copy the blobs to userspace
if the firmware command failed. If the failure was due to an invalid
length, i.e. the userspace buffer+length was too small, copying the number
of bytes _firmware_ requires will overflow the kernel-allocated buffer and
leak data to userspace.
BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
Read of size 2084 at addr ffff8885c4ab8aa0 by task syz.0.186/21033
CPU: 51 UID: 0 PID: 21033 Comm: syz.0.186 Tainted: G U O 7.0.0-smp-DEV #28 PREEMPTLAZY
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.84.12-0 11/17/2025
Call Trace:
<TASK>
dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120
print_address_description ../mm/kasan/report.c:378 [inline]
print_report+0xbc/0x260 ../mm/kasan/report.c:482
kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595
check_region_inline ../mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200
instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
_inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
_copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
copy_to_user ../include/linux/uaccess.h:236 [inline]
sev_ioctl_do_pdh_export+0x3d3/0x7c0 ../drivers/crypto/ccp/sev-dev.c:2347
sev_ioctl+0x2a2/0x490 ../drivers/crypto/ccp/sev-dev.c:2568
vfs_ioctl ../fs/ioctl.c:51 [inline]
__do_sys_ioctl ../fs/ioctl.c:597 [inline]
__se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583
do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
WARN if the driver says the command succeeded, but the firmware error code
says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any
firwmware error.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-05-01