Linux: >> Linux Kernel >> 4.19.276 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN
uart_write_room() and uart_write() behave inconsistently when
xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were
never properly initialized):
- uart_write_room() returns kfifo_avail() which can be > 0
- uart_write() checks xmit_buf and returns 0 if NULL
This inconsistency causes an infinite loop in drivers that rely on
tty_write_room() to determine if they can write:
while (tty_write_room(tty) > 0) {
written = tty->ops->write(...);
// written is always 0, loop never exits
}
For example, caif_serial's handle_tx() enters an infinite loop when
used with PORT_UNKNOWN serial ports, causing system hangs.
Fix by making uart_write_room() also check xmit_buf and return 0 if
it's NULL, consistent with uart_write().
Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: HIDP: Fix possible UAF
This fixes the following trace caused by not dropping l2cap_conn
reference when user->remove callback is called:
[ 97.809249] l2cap_conn_free: freeing conn ffff88810a171c00
[ 97.809907] CPU: 1 UID: 0 PID: 1419 Comm: repro_standalon Not tainted 7.0.0-rc1-dirty #14 PREEMPT(lazy)
[ 97.809935] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 97.809947] Call Trace:
[ 97.809954] <TASK>
[ 97.809961] dump_stack_lvl (lib/dump_stack.c:122)
[ 97.809990] l2cap_conn_free (net/bluetooth/l2cap_core.c:1808)
[ 97.810017] l2cap_conn_del (./include/linux/kref.h:66 net/bluetooth/l2cap_core.c:1821 net/bluetooth/l2cap_core.c:1798)
[ 97.810055] l2cap_disconn_cfm (net/bluetooth/l2cap_core.c:7347 (discriminator 1) net/bluetooth/l2cap_core.c:7340 (discriminator 1))
[ 97.810086] ? __pfx_l2cap_disconn_cfm (net/bluetooth/l2cap_core.c:7341)
[ 97.810117] hci_conn_hash_flush (./include/net/bluetooth/hci_core.h:2152 (discriminator 2) net/bluetooth/hci_conn.c:2644 (discriminator 2))
[ 97.810148] hci_dev_close_sync (net/bluetooth/hci_sync.c:5360)
[ 97.810180] ? __pfx_hci_dev_close_sync (net/bluetooth/hci_sync.c:5285)
[ 97.810212] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810242] ? up_write (./arch/x86/include/asm/atomic64_64.h:87 (discriminator 5) ./include/linux/atomic/atomic-arch-fallback.h:2852 (discriminator 5) ./include/linux/atomic/atomic-long.h:268 (discriminator 5) ./include/linux/atomic/atomic-instrumented.h:3391 (discriminator 5) kernel/locking/rwsem.c:1385 (discriminator 5) kernel/locking/rwsem.c:1643 (discriminator 5))
[ 97.810267] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810290] ? rcu_is_watching (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/context_tracking.h:128 kernel/rcu/tree.c:752)
[ 97.810320] hci_unregister_dev (net/bluetooth/hci_core.c:504 net/bluetooth/hci_core.c:2716)
[ 97.810346] vhci_release (drivers/bluetooth/hci_vhci.c:691)
[ 97.810375] ? __pfx_vhci_release (drivers/bluetooth/hci_vhci.c:678)
[ 97.810404] __fput (fs/file_table.c:470)
[ 97.810430] task_work_run (kernel/task_work.c:235)
[ 97.810451] ? __pfx_task_work_run (kernel/task_work.c:201)
[ 97.810472] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810495] ? do_raw_spin_unlock (./include/asm-generic/qspinlock.h:128 (discriminator 5) kernel/locking/spinlock_debug.c:142 (discriminator 5))
[ 97.810527] do_exit (kernel/exit.c:972)
[ 97.810547] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810574] ? __pfx_do_exit (kernel/exit.c:897)
[ 97.810594] ? lock_acquire (kernel/locking/lockdep.c:470 (discriminator 6) kernel/locking/lockdep.c:5870 (discriminator 6) kernel/locking/lockdep.c:5825 (discriminator 6))
[ 97.810616] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810639] ? do_raw_spin_lock (kernel/locking/spinlock_debug.c:95 (discriminator 4) kernel/locking/spinlock_debug.c:118 (discriminator 4))
[ 97.810664] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810688] ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[ 97.810721] do_group_exit (kernel/exit.c:1093)
[ 97.810745] get_signal (kernel/signal.c:3007 (discriminator 1))
[ 97.810772] ? security_file_permission (./arch/x86/include/asm/jump_label.h:37 security/security.c:2366)
[ 97.810803] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810826] ? vfs_read (fs/read_write.c:555)
[ 97.810854] ? __pfx_get_signal (kernel/signal.c:2800)
[ 97.810880] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810905] ? __pfx_vfs_read (fs/read_write.c:555)
[ 97.810932] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810960] arch_do_signal_or_restart (arch/
---truncated---
CVSS Score
8.8
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
soc: fsl: qbman: fix race condition in qman_destroy_fq
When QMAN_FQ_FLAG_DYNAMIC_FQID is set, there's a race condition between
fq_table[fq->idx] state and freeing/allocating from the pool and
WARN_ON(fq_table[fq->idx]) in qman_create_fq() gets triggered.
Indeed, we can have:
Thread A Thread B
qman_destroy_fq() qman_create_fq()
qman_release_fqid()
qman_shutdown_fq()
gen_pool_free()
-- At this point, the fqid is available again --
qman_alloc_fqid()
-- so, we can get the just-freed fqid in thread B --
fq->fqid = fqid;
fq->idx = fqid * 2;
WARN_ON(fq_table[fq->idx]);
fq_table[fq->idx] = fq;
fq_table[fq->idx] = NULL;
And adding some logs between qman_release_fqid() and
fq_table[fq->idx] = NULL makes the WARN_ON() trigger a lot more.
To prevent that, ensure that fq_table[fq->idx] is set to NULL before
gen_pool_free() is called by using smp_wmb().
CVSS Score
4.7
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
In DecodeQ931(), the UserUserIE code path reads a 16-bit length from
the packet, then decrements it by 1 to skip the protocol discriminator
byte before passing it to DecodeH323_UserInformation(). If the encoded
length is 0, the decrement wraps to -1, which is then passed as a
large value to the decoder, leading to an out-of-bounds read.
Add a check to ensure len is positive after the decrement.
CVSS Score
9.1
EPSS Score
0.001
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
In decode_int(), the CONS case calls get_bits(bs, 2) to read a length
value, then calls get_uint(bs, len) without checking that len bytes
remain in the buffer. The existing boundary check only validates the
2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint()
reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte
slab-out-of-bounds read.
Add a boundary check for len bytes after get_bits() and before
get_uint().
CVSS Score
8.2
EPSS Score
0.002
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()
sip_help_tcp() parses the SIP Content-Length header with
simple_strtoul(), which returns unsigned long, but stores the result in
unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are
silently truncated before computing the SIP message boundary.
For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32,
causing the parser to miscalculate where the current message ends. The
loop then treats trailing data in the TCP segment as a second SIP
message and processes it through the SDP parser.
Fix this by changing clen to unsigned long to match the return type of
simple_strtoul(), and reject Content-Length values that exceed the
remaining TCP payload length.
CVSS Score
8.6
EPSS Score
0.001
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()
ctnetlink_dump_exp_ct() stores a conntrack pointer in cb->data for the
netlink dump callback ctnetlink_exp_ct_dump_table(), but drops the
conntrack reference immediately after netlink_dump_start(). When the
dump spans multiple rounds, the second recvmsg() triggers the dump
callback which dereferences the now-freed conntrack via nfct_help(ct),
leading to a use-after-free on ct->ext.
The bug is that the netlink_dump_control has no .start or .done
callbacks to manage the conntrack reference across dump rounds. Other
dump functions in the same file (e.g. ctnetlink_get_conntrack) properly
use .start/.done callbacks for this purpose.
Fix this by adding .start and .done callbacks that hold and release the
conntrack reference for the duration of the dump, and move the
nfct_help() call after the cb->args[0] early-return check in the dump
callback to avoid dereferencing ct->ext unnecessarily.
BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0
Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133
CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY
Call Trace:
<TASK>
ctnetlink_exp_ct_dump_table+0x4f/0x2e0
netlink_dump+0x333/0x880
netlink_recvmsg+0x3e2/0x4b0
? aa_sk_perm+0x184/0x450
sock_recvmsg+0xde/0xf0
Allocated by task 133:
kmem_cache_alloc_noprof+0x134/0x440
__nf_conntrack_alloc+0xa8/0x2b0
ctnetlink_create_conntrack+0xa1/0x900
ctnetlink_new_conntrack+0x3cf/0x7d0
nfnetlink_rcv_msg+0x48e/0x510
netlink_rcv_skb+0xc9/0x1f0
nfnetlink_rcv+0xdb/0x220
netlink_unicast+0x3ec/0x590
netlink_sendmsg+0x397/0x690
__sys_sendmsg+0xf4/0x180
Freed by task 0:
slab_free_after_rcu_debug+0xad/0x1e0
rcu_core+0x5c3/0x9c0
CVSS Score
7.8
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect
syzkaller reported a bug [1], and the reproducer is available at [2].
ROSE sockets use four sk->sk_state values: TCP_CLOSE, TCP_LISTEN,
TCP_SYN_SENT, and TCP_ESTABLISHED. rose_connect() already rejects
calls for TCP_ESTABLISHED (-EISCONN) and TCP_CLOSE with SS_CONNECTING
(-ECONNREFUSED), but lacks a check for TCP_SYN_SENT.
When rose_connect() is called a second time while the first connection
attempt is still in progress (TCP_SYN_SENT), it overwrites
rose->neighbour via rose_get_neigh(). If that returns NULL, the socket
is left with rose->state == ROSE_STATE_1 but rose->neighbour == NULL.
When the socket is subsequently closed, rose_release() sees
ROSE_STATE_1 and calls rose_write_internal() ->
rose_transmit_link(skb, NULL), causing a NULL pointer dereference.
Per connect(2), a second connect() while a connection is already in
progress should return -EALREADY. Add this missing check for
TCP_SYN_SENT to complete the state validation in rose_connect().
[1] https://syzkaller.appspot.com/bug?extid=d00f90e0af54102fb271
[2] https://gist.github.com/mrpre/9e6779e0d13e2c66779b1653fef80516
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
net/sched: teql: Fix double-free in teql_master_xmit
Whenever a TEQL devices has a lockless Qdisc as root, qdisc_reset should
be called using the seq_lock to avoid racing with the datapath. Failure
to do so may cause crashes like the following:
[ 238.028993][ T318] BUG: KASAN: double-free in skb_release_data (net/core/skbuff.c:1139)
[ 238.029328][ T318] Free of addr ffff88810c67ec00 by task poc_teql_uaf_ke/318
[ 238.029749][ T318]
[ 238.029900][ T318] CPU: 3 UID: 0 PID: 318 Comm: poc_teql_ke Not tainted 7.0.0-rc3-00149-ge5b31d988a41 #704 PREEMPT(full)
[ 238.029906][ T318] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 238.029910][ T318] Call Trace:
[ 238.029913][ T318] <TASK>
[ 238.029916][ T318] dump_stack_lvl (lib/dump_stack.c:122)
[ 238.029928][ T318] print_report (mm/kasan/report.c:379 mm/kasan/report.c:482)
[ 238.029940][ T318] ? skb_release_data (net/core/skbuff.c:1139)
[ 238.029944][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
...
[ 238.029957][ T318] ? skb_release_data (net/core/skbuff.c:1139)
[ 238.029969][ T318] kasan_report_invalid_free (mm/kasan/report.c:221 mm/kasan/report.c:563)
[ 238.029979][ T318] ? skb_release_data (net/core/skbuff.c:1139)
[ 238.029989][ T318] check_slab_allocation (mm/kasan/common.c:231)
[ 238.029995][ T318] kmem_cache_free (mm/slub.c:2637 (discriminator 1) mm/slub.c:6168 (discriminator 1) mm/slub.c:6298 (discriminator 1))
[ 238.030004][ T318] skb_release_data (net/core/skbuff.c:1139)
...
[ 238.030025][ T318] sk_skb_reason_drop (net/core/skbuff.c:1256)
[ 238.030032][ T318] pfifo_fast_reset (./include/linux/ptr_ring.h:171 ./include/linux/ptr_ring.h:309 ./include/linux/skb_array.h:98 net/sched/sch_generic.c:827)
[ 238.030039][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
...
[ 238.030054][ T318] qdisc_reset (net/sched/sch_generic.c:1034)
[ 238.030062][ T318] teql_destroy (./include/linux/spinlock.h:395 net/sched/sch_teql.c:157)
[ 238.030071][ T318] __qdisc_destroy (./include/net/pkt_sched.h:328 net/sched/sch_generic.c:1077)
[ 238.030077][ T318] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)
[ 238.030089][ T318] ? __pfx_qdisc_graft (net/sched/sch_api.c:1091)
[ 238.030095][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 238.030102][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 238.030106][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 238.030114][ T318] tc_get_qdisc (net/sched/sch_api.c:1529 net/sched/sch_api.c:1556)
...
[ 238.072958][ T318] Allocated by task 303 on cpu 5 at 238.026275s:
[ 238.073392][ T318] kasan_save_stack (mm/kasan/common.c:58)
[ 238.073884][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5))
[ 238.074230][ T318] __kasan_slab_alloc (mm/kasan/common.c:369)
[ 238.074578][ T318] kmem_cache_alloc_node_noprof (./include/linux/kasan.h:253 mm/slub.c:4542 mm/slub.c:4869 mm/slub.c:4921)
[ 238.076091][ T318] kmalloc_reserve (net/core/skbuff.c:616 (discriminator 107))
[ 238.076450][ T318] __alloc_skb (net/core/skbuff.c:713)
[ 238.076834][ T318] alloc_skb_with_frags (./include/linux/skbuff.h:1383 net/core/skbuff.c:6763)
[ 238.077178][ T318] sock_alloc_send_pskb (net/core/sock.c:2997)
[ 238.077520][ T318] packet_sendmsg (net/packet/af_packet.c:2926 net/packet/af_packet.c:3019 net/packet/af_packet.c:3108)
[ 238.081469][ T318]
[ 238.081870][ T318] Freed by task 299 on cpu 1 at 238.028496s:
[ 238.082761][ T318] kasan_save_stack (mm/kasan/common.c:58)
[ 238.083481][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5))
[ 238.085348][ T318] kasan_save_free_info (mm/kasan/generic.c:587 (discriminator 1))
[ 238.085900][ T318] __kasan_slab_free (mm/
---truncated---
CVSS Score
7.8
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
PM: runtime: Fix a race condition related to device removal
The following code in pm_runtime_work() may dereference the dev->parent
pointer after the parent device has been freed:
/* Maybe the parent is now able to suspend. */
if (parent && !parent->power.ignore_children) {
spin_unlock(&dev->power.lock);
spin_lock(&parent->power.lock);
rpm_idle(parent, RPM_ASYNC);
spin_unlock(&parent->power.lock);
spin_lock(&dev->power.lock);
}
Fix this by inserting a flush_work() call in pm_runtime_remove().
Without this patch blktest block/001 triggers the following complaint
sporadically:
BUG: KASAN: slab-use-after-free in lock_acquire+0x70/0x160
Read of size 1 at addr ffff88812bef7198 by task kworker/u553:1/3081
Workqueue: pm pm_runtime_work
Call Trace:
<TASK>
dump_stack_lvl+0x61/0x80
print_address_description.constprop.0+0x8b/0x310
print_report+0xfd/0x1d7
kasan_report+0xd8/0x1d0
__kasan_check_byte+0x42/0x60
lock_acquire.part.0+0x38/0x230
lock_acquire+0x70/0x160
_raw_spin_lock+0x36/0x50
rpm_suspend+0xc6a/0xfe0
rpm_idle+0x578/0x770
pm_runtime_work+0xee/0x120
process_one_work+0xde3/0x1410
worker_thread+0x5eb/0xfe0
kthread+0x37b/0x480
ret_from_fork+0x6cb/0x920
ret_from_fork_asm+0x11/0x20
</TASK>
Allocated by task 4314:
kasan_save_stack+0x2a/0x50
kasan_save_track+0x18/0x40
kasan_save_alloc_info+0x3d/0x50
__kasan_kmalloc+0xa0/0xb0
__kmalloc_noprof+0x311/0x990
scsi_alloc_target+0x122/0xb60 [scsi_mod]
__scsi_scan_target+0x101/0x460 [scsi_mod]
scsi_scan_channel+0x179/0x1c0 [scsi_mod]
scsi_scan_host_selected+0x259/0x2d0 [scsi_mod]
store_scan+0x2d2/0x390 [scsi_mod]
dev_attr_store+0x43/0x80
sysfs_kf_write+0xde/0x140
kernfs_fop_write_iter+0x3ef/0x670
vfs_write+0x506/0x1470
ksys_write+0xfd/0x230
__x64_sys_write+0x76/0xc0
x64_sys_call+0x213/0x1810
do_syscall_64+0xee/0xfc0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
Freed by task 4314:
kasan_save_stack+0x2a/0x50
kasan_save_track+0x18/0x40
kasan_save_free_info+0x3f/0x50
__kasan_slab_free+0x67/0x80
kfree+0x225/0x6c0
scsi_target_dev_release+0x3d/0x60 [scsi_mod]
device_release+0xa3/0x220
kobject_cleanup+0x105/0x3a0
kobject_put+0x72/0xd0
put_device+0x17/0x20
scsi_device_dev_release+0xacf/0x12c0 [scsi_mod]
device_release+0xa3/0x220
kobject_cleanup+0x105/0x3a0
kobject_put+0x72/0xd0
put_device+0x17/0x20
scsi_device_put+0x7f/0xc0 [scsi_mod]
sdev_store_delete+0xa5/0x120 [scsi_mod]
dev_attr_store+0x43/0x80
sysfs_kf_write+0xde/0x140
kernfs_fop_write_iter+0x3ef/0x670
vfs_write+0x506/0x1470
ksys_write+0xfd/0x230
__x64_sys_write+0x76/0xc0
x64_sys_call+0x213/0x1810
CVSS Score
4.7
EPSS Score
0.0
Published
2026-04-03