Linux: >> Linux Kernel >> 4.19.316 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
mm/ksm: fix flag-dropping behavior in ksm_madvise
syzkaller discovered the following crash: (kernel BUG)
[ 44.607039] ------------[ cut here ]------------
[ 44.607422] kernel BUG at mm/userfaultfd.c:2067!
[ 44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)
[ 44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460
<snip other registers, drop unreliable trace>
[ 44.617726] Call Trace:
[ 44.617926] <TASK>
[ 44.619284] userfaultfd_release+0xef/0x1b0
[ 44.620976] __fput+0x3f9/0xb60
[ 44.621240] fput_close_sync+0x110/0x210
[ 44.622222] __x64_sys_close+0x8f/0x120
[ 44.622530] do_syscall_64+0x5b/0x2f0
[ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 44.623244] RIP: 0033:0x7f365bb3f227
Kernel panics because it detects UFFD inconsistency during
userfaultfd_release_all(). Specifically, a VMA which has a valid pointer
to vma->vm_userfaultfd_ctx, but no UFFD flags in vma->vm_flags.
The inconsistency is caused in ksm_madvise(): when user calls madvise()
with MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,
it accidentally clears all flags stored in the upper 32 bits of
vma->vm_flags.
Assuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and
int are 32-bit wide. This setup causes the following mishap during the &=
~VM_MERGEABLE assignment.
VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000.
After ~ is applied, it becomes 0x7fff'ffff unsigned int, which is then
promoted to unsigned long before the & operation. This promotion fills
upper 32 bits with leading 0s, as we're doing unsigned conversion (and
even for a signed conversion, this wouldn't help as the leading bit is 0).
& operation thus ends up AND-ing vm_flags with 0x0000'0000'7fff'ffff
instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears
the upper 32-bits of its value.
Fix it by changing `VM_MERGEABLE` constant to unsigned long, using the
BIT() macro.
Note: other VM_* flags are not affected: This only happens to the
VM_MERGEABLE flag, as the other VM_* flags are all constants of type int
and after ~ operation, they end up with leading 1 and are thus converted
to unsigned long with leading 1s.
Note 2:
After commit 31defc3b01d9 ("userfaultfd: remove (VM_)BUG_ON()s"), this is
no longer a kernel BUG, but a WARNING at the same place:
[ 45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067
but the root-cause (flag-drop) remains the same.
[akpm@linux-foundation.org: rust bindgen wasn't able to handle BIT(), from Miguel]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-28
In the Linux kernel, the following vulnerability has been resolved:
fbcon: fix integer overflow in fbcon_do_set_font
Fix integer overflow vulnerabilities in fbcon_do_set_font() where font
size calculations could overflow when handling user-controlled font
parameters.
The vulnerabilities occur when:
1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount
multiplication with user-controlled values that can overflow.
2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow
3. This results in smaller allocations than expected, leading to buffer
overflows during font data copying.
Add explicit overflow checking using check_mul_overflow() and
check_add_overflow() kernel helpers to safety validate all size
calculations before allocation.
CVSS Score
7.8
EPSS Score
0.0
Published
2025-10-15
In the Linux kernel, the following vulnerability has been resolved:
crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
Issuing two writes to the same af_alg socket is bogus as the
data will be interleaved in an unpredictable fashion. Furthermore,
concurrent writes may create inconsistencies in the internal
socket state.
Disallow this by adding a new ctx->write field that indiciates
exclusive ownership for writing.
CVSS Score
3.3
EPSS Score
0.0
Published
2025-10-13
In the Linux kernel, the following vulnerability has been resolved:
iommu/amd/pgtbl: Fix possible race while increase page table level
The AMD IOMMU host page table implementation supports dynamic page table levels
(up to 6 levels), starting with a 3-level configuration that expands based on
IOVA address. The kernel maintains a root pointer and current page table level
to enable proper page table walks in alloc_pte()/fetch_pte() operations.
The IOMMU IOVA allocator initially starts with 32-bit address and onces its
exhuasted it switches to 64-bit address (max address is determined based
on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU
driver increases page table level.
But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads
pgtable->[root/mode] without lock. So its possible that in exteme corner case,
when increase_address_space() is updating pgtable->[root/mode], fetch_pte()
reads wrong page table level (pgtable->mode). It does compare the value with
level encoded in page table and returns NULL. This will result is
iommu_unmap ops to fail and upper layer may retry/log WARN_ON.
CPU 0 CPU 1
------ ------
map pages unmap pages
alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte()
pgtable->root = pte (new root value)
READ pgtable->[mode/root]
Reads new root, old mode
Updates mode (pgtable->mode += 1)
Since Page table level updates are infrequent and already synchronized with a
spinlock, implement seqcount to enable lock-free read operations on the read path.
CVSS Score
4.7
EPSS Score
0.0
Published
2025-10-09
In the Linux kernel, the following vulnerability has been resolved:
tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().
syzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk
in the TCP_ESTABLISHED state. [0]
syzbot reused the server-side TCP Fast Open socket as a new client before
the TFO socket completes 3WHS:
1. accept()
2. connect(AF_UNSPEC)
3. connect() to another destination
As of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes
it to TCP_CLOSE and makes connect() possible, which restarts timers.
Since tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the
retransmit timer triggered the warning and the intended packet was not
retransmitted.
Let's call reqsk_fastopen_remove() in tcp_disconnect().
[0]:
WARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))
Modules linked in:
CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))
Code: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e
RSP: 0018:ffffc900002f8d40 EFLAGS: 00010293
RAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017
RDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400
RBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8
R10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540
R13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0
FS: 0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0
Call Trace:
<IRQ>
tcp_write_timer (net/ipv4/tcp_timer.c:738)
call_timer_fn (kernel/time/timer.c:1747)
__run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372)
timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135)
tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035)
__walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1))
tmigr_handle_remote (kernel/time/timer_migration.c:1096)
handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580)
irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35))
</IRQ>
CVSS Score
7.8
EPSS Score
0.0
Published
2025-10-09
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt7601u: fix an integer underflow
Fix an integer underflow that leads to a null pointer dereference in
'mt7601u_rx_skb_from_seg()'. The variable 'dma_len' in the URB packet
could be manipulated, which could trigger an integer underflow of
'seg_len' in 'mt7601u_rx_process_seg()'. This underflow subsequently
causes the 'bad_frame' checks in 'mt7601u_rx_skb_from_seg()' to be
bypassed, eventually leading to a dereference of the pointer 'p', which
is a null pointer.
Ensure that 'dma_len' is greater than 'min_seg_len'.
Found by a modified version of syzkaller.
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 12 Comm: ksoftirqd/0 Tainted: G W O 5.14.0+
#139
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
RIP: 0010:skb_add_rx_frag+0x143/0x370
Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44
89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02
00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00
RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8
RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010
R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000
R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff88811a800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
mt7601u_rx_tasklet+0xc73/0x1270
? mt7601u_submit_rx_buf.isra.0+0x510/0x510
? tasklet_action_common.isra.0+0x79/0x2f0
tasklet_action_common.isra.0+0x206/0x2f0
__do_softirq+0x1b5/0x880
? tasklet_unlock+0x30/0x30
run_ksoftirqd+0x26/0x50
smpboot_thread_fn+0x34f/0x7d0
? smpboot_register_percpu_thread+0x370/0x370
kthread+0x3a1/0x480
? set_kthread_struct+0x120/0x120
ret_from_fork+0x1f/0x30
Modules linked in: 88XXau(O) 88x2bu(O)
---[ end trace 57f34f93b4da0f9b ]---
RIP: 0010:skb_add_rx_frag+0x143/0x370
Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44
89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02
00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00
RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8
RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010
R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000
R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff88811a800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Avoid calling OPDESC() with ops->opnum == OP_ILLEGAL
OPDESC() simply indexes into nfsd4_ops[] by the op's operation
number, without range checking that value. It assumes callers are
careful to avoid calling it with an out-of-bounds opnum value.
nfsd4_decode_compound() is not so careful, and can invoke OPDESC()
with opnum set to OP_ILLEGAL, which is 10044 -- well beyond the end
of nfsd4_ops[].
CVSS Score
7.8
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (xgene) Fix ioremap and memremap leak
Smatch reports:
drivers/hwmon/xgene-hwmon.c:757 xgene_hwmon_probe() warn:
'ctx->pcc_comm_addr' from ioremap() not released on line: 757.
This is because in drivers/hwmon/xgene-hwmon.c:701 xgene_hwmon_probe(),
ioremap and memremap is not released, which may cause a leak.
To fix this, ioremap and memremap is modified to devm_ioremap and
devm_memremap.
[groeck: Fixed formatting and subject]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
tun: Fix memory leak for detached NAPI queue.
syzkaller reported [0] memory leaks of sk and skb related to the TUN
device with no repro, but we can reproduce it easily with:
struct ifreq ifr = {}
int fd_tun, fd_tmp;
char buf[4] = {};
fd_tun = openat(AT_FDCWD, "/dev/net/tun", O_WRONLY, 0);
ifr.ifr_flags = IFF_TUN | IFF_NAPI | IFF_MULTI_QUEUE;
ioctl(fd_tun, TUNSETIFF, &ifr);
ifr.ifr_flags = IFF_DETACH_QUEUE;
ioctl(fd_tun, TUNSETQUEUE, &ifr);
fd_tmp = socket(AF_PACKET, SOCK_PACKET, 0);
ifr.ifr_flags = IFF_UP;
ioctl(fd_tmp, SIOCSIFFLAGS, &ifr);
write(fd_tun, buf, sizeof(buf));
close(fd_tun);
If we enable NAPI and multi-queue on a TUN device, we can put skb into
tfile->sk.sk_write_queue after the queue is detached. We should prevent
it by checking tfile->detached before queuing skb.
Note this must be done under tfile->sk.sk_write_queue.lock because write()
and ioctl(IFF_DETACH_QUEUE) can run concurrently. Otherwise, there would
be a small race window:
write() ioctl(IFF_DETACH_QUEUE)
`- tun_get_user `- __tun_detach
|- if (tfile->detached) |- tun_disable_queue
| `-> false | `- tfile->detached = tun
| `- tun_queue_purge
|- spin_lock_bh(&queue->lock)
`- __skb_queue_tail(queue, skb)
Another solution is to call tun_queue_purge() when closing and
reattaching the detached queue, but it could paper over another
problems. Also, we do the same kind of test for IFF_NAPI_FRAGS.
[0]:
unreferenced object 0xffff88801edbc800 (size 2048):
comm "syz-executor.1", pid 33269, jiffies 4295743834 (age 18.756s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............
backtrace:
[<000000008c16ea3d>] __do_kmalloc_node mm/slab_common.c:965 [inline]
[<000000008c16ea3d>] __kmalloc+0x4a/0x130 mm/slab_common.c:979
[<000000003addde56>] kmalloc include/linux/slab.h:563 [inline]
[<000000003addde56>] sk_prot_alloc+0xef/0x1b0 net/core/sock.c:2035
[<000000003e20621f>] sk_alloc+0x36/0x2f0 net/core/sock.c:2088
[<0000000028e43843>] tun_chr_open+0x3d/0x190 drivers/net/tun.c:3438
[<000000001b0f1f28>] misc_open+0x1a6/0x1f0 drivers/char/misc.c:165
[<000000004376f706>] chrdev_open+0x111/0x300 fs/char_dev.c:414
[<00000000614d379f>] do_dentry_open+0x2f9/0x750 fs/open.c:920
[<000000008eb24774>] do_open fs/namei.c:3636 [inline]
[<000000008eb24774>] path_openat+0x143f/0x1a30 fs/namei.c:3791
[<00000000955077b5>] do_filp_open+0xce/0x1c0 fs/namei.c:3818
[<00000000b78973b0>] do_sys_openat2+0xf0/0x260 fs/open.c:1356
[<00000000057be699>] do_sys_open fs/open.c:1372 [inline]
[<00000000057be699>] __do_sys_openat fs/open.c:1388 [inline]
[<00000000057be699>] __se_sys_openat fs/open.c:1383 [inline]
[<00000000057be699>] __x64_sys_openat+0x83/0xf0 fs/open.c:1383
[<00000000a7d2182d>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<00000000a7d2182d>] do_syscall_64+0x3c/0x90 arch/x86/entry/common.c:80
[<000000004cc4e8c4>] entry_SYSCALL_64_after_hwframe+0x72/0xdc
unreferenced object 0xffff88802f671700 (size 240):
comm "syz-executor.1", pid 33269, jiffies 4295743854 (age 18.736s)
hex dump (first 32 bytes):
68 c9 db 1e 80 88 ff ff 68 c9 db 1e 80 88 ff ff h.......h.......
00 c0 7b 2f 80 88 ff ff 00 c8 db 1e 80 88 ff ff ..{/............
backtrace:
[<00000000e9d9fdb6>] __alloc_skb+0x223/0x250 net/core/skbuff.c:644
[<000000002c3e4e0b>] alloc_skb include/linux/skbuff.h:1288 [inline]
[<000000002c3e4e0b>] alloc_skb_with_frags+0x6f/0x350 net/core/skbuff.c:6378
[<00000000825f98d7>] sock_alloc_send_pskb+0x3ac/0x3e0 net/core/sock.c:2729
[<00000000e9eb3df3>] tun_alloc_skb drivers/net/tun.c:1529 [inline]
[<
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
bnxt: avoid overflow in bnxt_get_nvram_directory()
The value of an arithmetic expression is subject
of possible overflow due to a failure to cast operands to a larger data
type before performing arithmetic. Used macro for multiplication instead
operator for avoiding overflow.
Found by Security Code and Linux Verification
Center (linuxtesting.org) with SVACE.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07