Linux: >> Linux Kernel >> 4.13.8 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Fix shadow paging use-after-free due to unexpected role
Commit 0cb2af2ea66ad ("KVM: x86: Fix shadow paging use-after-free due
to unexpected GFN") fixed a shadow paging mismatch between stored and
computed GFNs; the bug could be triggered by changing a PDE mapping from
outside the guest, and then deleting a memslot. The rmap_remove()
call would miss entries created after the PDE change because the GFN
of the leaf SPTE does not match the GFN of the struct kvm_mmu_page.
A similar hole however remains if the modified PDE points to a non-leaf
page. In this case the gfn can be made to match, but the role does not
match: the original large 2MB page creates a kvm_mmu_page with direct=1,
while the new 4KB needs a kvm_mmu_page with direct=0. However,
kvm_mmu_get_child_sp() does not compare the role, and therefore reuses
the page.
The next step is installing a leaf (4KB) SPTE on the new path which
records an rmap entry under the gfn resolved by the walk. But when
that child is zapped its parent kvm_mmu_page has direct=1 and
kvm_mmu_page_get_gfn() computes the gfn for the 4KB page as
sp->gfn + index instead of using sp->shadowed_translation[] (or sp->gfns[]
in older kernels). It therefore fails to remove the recorded entry.
When the memslot is dropped the shadow page is freed but the rmap
entry survives, as in the scenario that was already fixed. Code that
later walks that gfn (dirty logging, MMU notifier invalidation, and
so on) dereferences an sptep that lies in the freed page, causing the
use-after-free.
CVSS Score
8.8
EPSS Score
0.009
Published
2026-07-04
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen()
l2cap_chan_close() removes the channel from conn->chan_l, which
must be done under conn->lock. cleanup_listen() runs under the
parent sk_lock, so acquiring conn->lock would invert the
established conn->lock -> chan->lock -> sk_lock order.
Instead of calling l2cap_chan_close() directly, schedule
l2cap_chan_timeout with delay 0 to close the channel
asynchronously. The timeout handler already acquires conn->lock
and chan->lock in the correct order.
The timer is only armed when chan->conn is still set: if it is
already NULL, l2cap_conn_del() has already processed this channel
(l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb),
so there is nothing left to do. If l2cap_conn_del() races in
after the timer is armed, __clear_chan_timer() inside
l2cap_chan_del() cancels it; if the timer has already fired, the
handler returns harmlessly because chan->conn was cleared.
CVSS Score
8.8
EPSS Score
0.002
Published
2026-07-02
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack: destroy stale expectfn expectations on unregister
NAT helpers such as nf_nat_h323 store a raw pointer to module text in
exp->expectfn (e.g. ip_nat_q931_expect). nf_ct_helper_expectfn_unregister()
only unlinks the callback descriptor and never walks the expectation table,
so an expectation pending at module removal survives with a dangling
exp->expectfn into freed module text.
When the expected connection arrives, init_conntrack() invokes
exp->expectfn(), now a stale pointer into the unloaded module. Reproduced
on a KASAN build by loading the H.323 helpers, creating a Q.931
expectation, unloading nf_nat_h323, then connecting to the expected port:
Oops: int3: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:0xffffffffa06102d1
init_conntrack.isra.0 (net/netfilter/nf_conntrack_core.c:1862)
nf_conntrack_in (net/netfilter/nf_conntrack_core.c:2049)
ipv4_conntrack_local (net/netfilter/nf_conntrack_proto.c:223)
nf_hook_slow (net/netfilter/core.c:619)
__ip_local_out (net/ipv4/ip_output.c:120)
__tcp_transmit_skb (net/ipv4/tcp_output.c:1715)
tcp_connect (net/ipv4/tcp_output.c:4374)
tcp_v4_connect (net/ipv4/tcp_ipv4.c:345)
__sys_connect (net/socket.c:2167)
Modules linked in: nf_conntrack_h323 [last unloaded: nf_nat_h323]
Reaching the dangling state requires CAP_SYS_MODULE in the initial user
namespace to remove a NAT helper that still has live expectations, so this
is a robustness fix; leaving an expectation pointing at freed text is wrong
regardless.
Add nf_ct_helper_expectfn_destroy(), which walks the expectation table and
drops every expectation whose ->expectfn matches the descriptor being torn
down. Call it from each NAT helper's exit path after the existing RCU grace
period, so no expectation outlives the code it points at and no extra
synchronize_rcu() is introduced. With the fix, the same reproducer runs to
completion without the Oops.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-01
In the Linux kernel, the following vulnerability has been resolved:
signal: clear JOBCTL_PENDING_MASK for caller in zap_other_threads()
When a multi-threaded process receives a stop signal (e.g., SIGSTOP),
do_signal_stop() sets JOBCTL_STOP_PENDING and JOBCTL_STOP_CONSUME on all
threads and sets signal->group_stop_count to the number of threads. If
one of the threads concurrently calls execve(), de_thread() invokes
zap_other_threads() to kill all other threads. zap_other_threads()
aborts the pending group stop by resetting signal->group_stop_count to 0
and clears the JOBCTL_PENDING_MASK for all other threads. However, it
fails to clear the job control flags for the calling thread.
When execve() completes, the calling thread returns to user mode and
checks for pending signals. Seeing the stale JOBCTL_STOP_PENDING flag,
it calls do_signal_stop(), which invokes task_participate_group_stop().
Since JOBCTL_STOP_CONSUME is still set, it attempts to decrement the
already-zero signal->group_stop_count, triggering a warning:
sig->group_stop_count == 0
WARNING: CPU: 1 PID: 6475 at kernel/signal.c:373
task_participate_group_stop+0x215/0x2d0
Call Trace:
<TASK>
do_signal_stop+0x3be/0x5c0 kernel/signal.c:2619
get_signal+0xa8c/0x1330 kernel/signal.c:2884
arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98
do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Fix this race condition by clearing the JOBCTL_PENDING_MASK for the
calling thread in zap_other_threads(), ensuring it does not retain any
stale job control state after the thread group is destroyed. This aligns
with other functions that tear down a thread group and abort group
stops, such as zap_process() and complete_signal(), which correctly
clear these flags for all threads including the current one.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-07-01
In the Linux kernel, the following vulnerability has been resolved:
hsr: Remove WARN_ONCE() in hsr_addr_is_self().
syzbot reported the warning [0] in hsr_addr_is_self(),
whose assumption is simply wrong.
hsr->self_node is cleared in hsr_del_self_node(), which
is called from hsr_dellink().
Since dev->rtnl_link_ops->dellink() is called before
unregister_netdevice_many(), there is a window when
user can find the device but without hsr->self_node.
Let's remove WARN_ONCE() in hsr_addr_is_self().
[0]:
HSR: No self node
WARNING: net/hsr/hsr_framereg.c:39 at hsr_addr_is_self+0x211/0x3f0 net/hsr/hsr_framereg.c:39, CPU#0: syz.4.16848/17220
Modules linked in:
CPU: 0 UID: 0 PID: 17220 Comm: syz.4.16848 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:hsr_addr_is_self+0x211/0x3f0 net/hsr/hsr_framereg.c:39
Code: 33 2f 41 0f b7 dd 89 ee 09 de 31 ff e8 c8 b4 c6 f6 09 dd 74 54 e8 0f b0 c6 f6 31 ed eb 53 e8 06 b0 c6 f6 48 8d 3d 2f 50 9c 04 <67> 48 0f b9 3a 31 ed eb 42 e8 c1 13 1f 00 89 c5 31 ff 89 c6 e8 96
RSP: 0018:ffffc900041c70e0 EFLAGS: 00010283
RAX: ffffffff8afdc6ca RBX: ffffffff8afdc4e6 RCX: 0000000000080000
RDX: ffffc90010493000 RSI: 0000000000000948 RDI: ffffffff8f9a1700
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc900041c71e8 R11: fffff52000838e3f R12: dffffc0000000000
R13: ffff888041f9e3c0 R14: ffff888086ee3802 R15: 0000000000000000
FS: 00007f6fe985d6c0(0000) GS:ffff888126176000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80bd437dac CR3: 0000000025096000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
check_local_dest net/hsr/hsr_forward.c:592 [inline]
fill_frame_info net/hsr/hsr_forward.c:728 [inline]
hsr_forward_skb+0xa11/0x2a80 net/hsr/hsr_forward.c:739
hsr_dev_xmit+0x253/0x370 net/hsr/hsr_device.c:236
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2df/0x860 net/core/dev.c:3904
__dev_queue_xmit+0x1428/0x3900 net/core/dev.c:4870
neigh_output include/net/neighbour.h:556 [inline]
ip_finish_output2+0xcec/0x10b0 net/ipv4/ip_output.c:237
ip_send_skb net/ipv4/ip_output.c:1510 [inline]
ip_push_pending_frames+0x8b/0x110 net/ipv4/ip_output.c:1530
raw_sendmsg+0x1547/0x1a50 net/ipv4/raw.c:659
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x7da/0x9c0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1c3/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6feb62ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6fe985d028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6feb8a6090 RCX: 00007f6feb62ce59
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007f6feb6c2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6feb8a6128 R14: 00007f6feb8a6090 R15: 00007ffcf01cc488
</TASK>
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-01
In the Linux kernel, the following vulnerability has been resolved:
arm64: errata: Mitigate TLBI errata on various Arm CPUs
A number of CPUs developed by Arm suffer from errata whereby a broadcast
TLBI;DSB sequence may complete before the global observation of writes
which are translated by an affected TLB entry.
These errata ONLY affect the completion of memory accesses which have
been translated by an invalidated TLB entry, and these errata DO NOT
affect the actual invalidation of TLB entries. TLB entries are removed
correctly.
This issue has been assigned CVE ID CVE-2025-10263.
To mitigate this issue, Arm recommends that software follows any
affected TLBI;DSB sequence with an additional TLBI;DSB, which will
ensure that all memory write effects affected by the first TLBI have
been globally observed. The additional TLBI can use any operation that
is broadcast to affected CPUs, and the additional DSB can use any option
that is sufficient to complete the additional TLBI.
The ARM64_WORKAROUND_REPEAT_TLBI workaround is sufficient to mitigate
the issue. Enable this workaround for affected CPUs, and update the
silicon errata documentation accordingly.
Note that due to the manner in which Arm develops IP and tracks errata,
some CPUs share a common erratum number.
CVSS Score
8.8
EPSS Score
0.001
Published
2026-07-01
In the Linux kernel, the following vulnerability has been resolved:
net: rds: clear i_sends on setup unwind
The RDS IB connection teardown path is written so it can run during
partial startup and on repeated shutdown attempts. It uses NULL
pointers to distinguish resources that are still owned from resources
that have already been released.
When rds_ib_setup_qp() fails after allocating i_sends but before
allocating i_recvs, the sends_out path frees i_sends without clearing
the pointer. A later shutdown pass can still treat that stale pointer
as a live send ring allocation.
Clear i_sends after vfree() in the error unwind path so the existing
shutdown logic continues to use the correct ownership state.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-07-01
In the Linux kernel, the following vulnerability has been resolved:
agp/amd64: Fix broken error propagation in agp_amd64_probe()
A NULL pointer dereference was observed in the AMD64 AGP driver when
running in a virtualized environment (e.g. qemu/kvm) without a physical
AMD northbridge. The crash occurs in amd64_fetch_size() when attempting
to dereference the pointer returned by node_to_amd_nb(0).
The root cause of this crash is broken error propagation in
agp_amd64_probe(): When no AMD northbridges are found, cache_nbs()
correctly returns -ENODEV. However, the probe function erroneously
checks the return value against exactly -1, rather than < 0.
As a result, the hardware absence error is masked, allowing the driver
to improperly proceed with initialization. It eventually calls
agp_add_bridge(), which invokes amd64_fetch_size(). Since the hardware
does not exist, node_to_amd_nb(0) returns NULL, leading to a General
Protection Fault (GPF) when accessing its ->misc member.
Fix the issue by correcting the error check in agp_amd64_probe() to
abort properly when cache_nbs() returns any negative error code. This
prevents the driver from erroneously proceeding without hardware, thereby
avoiding the subsequent NULL pointer dereference at its source.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-29
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty()
nilfs_ioctl_mark_blocks_dirty() uses bd_oblocknr to detect dead blocks
by comparing it with the current block number bd_blocknr. If they differ,
the block is considered dead and skipped.
However, bd_oblocknr should never be 0 since block 0 typically stores the
primary superblock and is never a valid GC target block. A corrupted ioctl
request with bd_oblocknr set to 0 causes the comparison to incorrectly
match when the lookup returns -ENOENT and sets bd_blocknr to 0, bypassing
the dead block check and calling nilfs_bmap_mark() on a non-existent
block. This causes nilfs_btree_do_lookup() to return -ENOENT, triggering
the WARN_ON(ret == -ENOENT).
Fix this by rejecting ioctl requests with bd_oblocknr set to 0 at the
beginning of each iteration.
[ryusuke: slightly modified the commit message and comments for accuracy]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-26
In the Linux kernel, the following vulnerability has been resolved:
ocfs2/dlm: fix off-by-one in dlm_match_regions() region comparison
The local-vs-remote region comparison loop uses '<=' instead of '<',
causing it to read one entry past the valid range of qr_regions. The
other loops in the same function correctly use '<'.
Fix the loop condition to use '<' for consistency and correctness.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-06-26
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