Linux: >> Linux Kernel >> 6.18.36 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
i2c: stub: Reject I2C block transfers with invalid length
The I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data->block[0]
as the transfer length. The existing check only clamps it to avoid
overrunning the chip->words[256] register array, but does not validate
it against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union
i2c_smbus_data.block buffer (34 bytes total). The driver is a
development/test tool (CONFIG_I2C_STUB=m, not built by default)
that must be loaded with a chip_addr= parameter.
A local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl
with I2C_SMBUS_I2C_BLOCK_DATA and data->block[0] > 32, causing
stub_xfer() to read or write past the end of the union
i2c_smbus_data.block buffer:
BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223)
Read of size 1 at addr ffff88800abcfd92 by task exploit/81
Call Trace:
<TASK>
stub_xfer (drivers/i2c/i2c-stub.c:223)
__i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593)
i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536)
i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391)
i2cdev_ioctl (drivers/i2c/i2c-dev.c:478)
__x64_sys_ioctl (fs/ioctl.c:583)
do_syscall_64 (arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
</TASK>
The bug exists because i2c-stub implements .smbus_xfer directly,
bypassing the I2C_SMBUS_BLOCK_MAX validation in
i2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same
function correctly validates against I2C_SMBUS_BLOCK_MAX, but the
I2C_SMBUS_I2C_BLOCK_DATA case does not.
Fix by rejecting transfers with data->block[0] == 0 or
data->block[0] > I2C_SMBUS_BLOCK_MAX with -EINVAL, consistent with
both the I2C_SMBUS_BLOCK_DATA case in the same function and the
I2C_SMBUS_I2C_BLOCK_DATA validation in i2c_smbus_xfer_emulated().
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized
When CONFIG_BPF_LSM=y is set, BPF inode storage maps
(BPF_MAP_TYPE_INODE_STORAGE) are compiled into the kernel. However,
if the BPF LSM is not explicitly enabled at boot time (e.g. omitted
from the "lsm=" boot parameter), lsm_prepare() is never executed for
the BPF LSM.
Consequently, the BPF inode security blob offset
(bpf_lsm_blob_sizes.lbs_inode) is never initialized and remains at
its default compiled size of 8 bytes instead of being updated to a
valid offset past the reserved struct rcu_head (typically 16 bytes
or more).
When a privileged user creates and updates a BPF_MAP_TYPE_INODE_STORAGE
map, bpf_inode() evaluates inode->i_security + 8. This erroneously
aliases the struct rcu_head.func callback pointer at the beginning
of the inode->i_security blob. During subsequent map element cleanup
or inode destruction, writing NULL to owner_storage clears the queued
RCU callback pointer. When rcu_do_batch() later executes the queued
callback, it attempts an instruction fetch at address 0x0, triggering
an immediate kernel panic.
Fix this by introducing a global bpf_lsm_initialized boolean flag
marked with __ro_after_init. Set this flag to true inside bpf_lsm_init()
when the LSM framework successfully registers the BPF LSM. Gate map
allocation in inode_storage_map_alloc() on this flag, returning
-EOPNOTSUPP if the BPF LSM is in turn uninitialized.
This fail-fast approach prevents userspace from allocating inode
storage maps when the supporting BPF LSM infrastructure is absent,
avoiding zombie map states.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
i2c: i801: fix hardware state machine corruption in error path
A severe livelock and subsequent Hung Task panic were observed in the
i2c-i801 driver during concurrent Fuzzing. The crash is caused by an
unconditional hardware register cleanup in the error handling path of
i801_access().
When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus
controller is actively used by BIOS/ACPI), the kernel does not actually
acquire the hardware ownership. However, the code jumps to the 'out'
label and executes:
iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv));
This forcefully clears the INUSE_STS lock and resets the hardware status
flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI
transactions and totally corrupts the SMBus hardware state machine.
Consequently, all subsequent i801_access() calls fail at the pre-check
stage, triggering an endless stream of "SMBus is busy, can't use it!"
error logs. Over a slow serial console, this printk flood monopolizes
the CPU (Console Livelock), starving other processes trying to acquire
the mmap_lock down_read semaphore, ultimately triggering the hung task
watchdog.
Fix this by moving the 'out' label below the hardware register cleanup.
If i801_check_pre() fails, we safely bypass the iowrite8() and only
release the software locks (pm_runtime and mutex), strictly adhering to
the rule of not releasing resources that were never acquired.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: cancel pending_rx_work before taking conn->lock
l2cap_conn_del() takes conn->lock and then calls cancel_work_sync() for
pending_rx_work. process_pending_rx() takes the same mutex, so teardown
can deadlock against the worker it is flushing.
This issue was found by our static analysis tool and then manually
reviewed against the current tree.
The grounded PoC kept the l2cap_conn_ready() -> queue_work(...,
&conn->pending_rx_work) submit path, the l2cap_conn_del() ->
cancel_work_sync(&conn->pending_rx_work) teardown path, and the
process_pending_rx() -> mutex_lock(&conn->lock) worker edge. Lockdep
WARNING: possible circular locking dependency detected
process_pending_rx+0x21/0x2a [vuln_msv]
l2cap_conn_del.constprop.0+0x3f/0x4e [vuln_msv]
*** DEADLOCK ***
Cancel pending_rx_work before taking conn->lock, matching the existing
lock-before-drain ordering used for the two delayed works in the same
teardown path. The pending_rx queue is still purged after the work has
been cancelled and conn->lock has been acquired.
CVSS Score
8.8
EPSS Score
0.003
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
xfs: fail recovery on a committed log item with no regions
If the first op of a transaction is a bare transaction header
(len == sizeof(struct xfs_trans_header)), xlog_recover_add_to_trans()
adds an item but no region, leaving it on r_itemq with ri_cnt == 0 and
ri_buf == NULL.
The header can be split across op records, so later ops may still add
regions; the item is only invalid if the transaction commits with none.
The runtime commit path never emits such a transaction, so this only
happens on a crafted log. It came from an AI-assisted code audit of the
recovery parser.
xlog_recover_reorder_trans() calls ITEM_TYPE() on the item, which reads
*(unsigned short *)item->ri_buf[0].iov_base and faults on the NULL
ri_buf. Reject it there, before the commit handlers that also read
ri_buf[0].
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:xlog_recover_reorder_trans (fs/xfs/xfs_log_recover.c:1836)
xlog_recover_commit_trans (fs/xfs/xfs_log_recover.c:2043)
xlog_recover_process_data (fs/xfs/xfs_log_recover.c:2501)
xlog_do_recovery_pass (fs/xfs/xfs_log_recover.c:3244)
xlog_recover (fs/xfs/xfs_log_recover.c:3493)
xfs_log_mount (fs/xfs/xfs_log.c:618)
xfs_mountfs (fs/xfs/xfs_mount.c:1034)
xfs_fs_fill_super (fs/xfs/xfs_super.c:1938)
vfs_get_tree (fs/super.c:1695)
path_mount (fs/namespace.c:4161)
__x64_sys_mount (fs/namespace.c:4367)
CVSS Score
5.5
EPSS Score
0.002
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
net: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink()
rmnet_dellink() removes the endpoint from the hash table with
hlist_del_init_rcu() and then immediately frees it with kfree(). However,
RCU readers on the receive path (rmnet_rx_handler ->
__rmnet_map_ingress_handler) may still hold a reference to the endpoint and
dereference ep->egress_dev after the memory has been freed. The endpoint is
a kmalloc-32 object, and the stale read at offset 8 corresponds to the
egress_dev pointer.
BUG: unable to handle page fault for address: ffffffffde942eef
Oops: 0002 [#1] SMP NOPTI
CPU: 1 UID: 0 PID: 137 Comm: poc_write Not tainted 7.0.0+ #4 PREEMPTLAZY
RIP: 0010:rmnet_vnd_rx_fixup (rmnet_vnd.c:27)
Call Trace:
<TASK>
__rmnet_map_ingress_handler (rmnet_handlers.c:48 rmnet_handlers.c:101)
rmnet_rx_handler (rmnet_handlers.c:129 rmnet_handlers.c:235)
__netif_receive_skb_core.constprop.0 (net/core/dev.c:6096)
__netif_receive_skb_one_core (net/core/dev.c:6208)
netif_receive_skb (net/core/dev.c:6467)
tun_get_user (drivers/net/tun.c:1955)
tun_chr_write_iter (drivers/net/tun.c:2003)
vfs_write (fs/read_write.c:688)
ksys_write (fs/read_write.c:740)
</TASK>
Add an rcu_head field to struct rmnet_endpoint and replace kfree() with
kfree_rcu() so the endpoint memory remains valid through the RCU grace
period. Also remove the rmnet_vnd_dellink() call and inline only the
nr_rmnet_devs decrement, since rmnet_vnd_dellink() would set
ep->egress_dev to NULL during the grace period, creating a data race
with lockless readers.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ipset: fix race between dump and ip_set_list resize
The release path of ip_set_dump_do() and ip_set_dump_done() read
inst->ip_set_list via ip_set_ref_netlink(), a plain rcu_dereference_raw()
of the array pointer. These run from netlink_recvmsg() without the nfnl
mutex and without an RCU read-side critical section.
A concurrent ip_set_create() can grow the array: it publishes the new
array, calls synchronize_net() and then kvfree()s the old one. Since the
dump paths read the array outside any RCU reader, synchronize_net() does
not wait for them and the old array can be freed while they still index
into it, causing a use-after-free.
The dumped set itself stays pinned via set->ref_netlink, so only the
array load needs protecting. Take rcu_read_lock() around it, matching
ip_set_get_byname() and __ip_set_put_byindex().
BUG: KASAN: slab-use-after-free in ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1697)
Read of size 8 at addr ffff88800b5c4018 by task exploit/150
Call Trace:
...
kasan_report (mm/kasan/report.c:595)
ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1697)
netlink_dump (net/netlink/af_netlink.c:2325)
netlink_recvmsg (net/netlink/af_netlink.c:1976)
sock_recvmsg (net/socket.c:1159)
__sys_recvfrom (net/socket.c:2315)
...
Oops: general protection fault, probably for non-canonical address ... KASAN NOPTI
KASAN: maybe wild-memory-access in range [0x02d6...d0-0x02d6...d7]
RIP: 0010:ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1698)
Kernel panic - not syncing: Fatal exception
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-20
In the Linux kernel, the following vulnerability has been resolved:
gfs2: fix use-after-free in gfs2_qd_dealloc
gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),
accesses the superblock object sdp through qd->qd_sbd after freeing qd.
It does so to decrement sd_quota_count and wake up sd_kill_wait.
However, by the time the RCU callback runs, gfs2_put_super() may have
already freed sdp via free_sbd(). This can happen when
gfs2_quota_cleanup() is called during unmount: it disposes of quota
objects via call_rcu() and then waits on sd_kill_wait with a 60-second
timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers
additional qd_put() calls that schedule more RCU callbacks after the
wait completes, gfs2_put_super() will proceed to free the superblock
while RCU callbacks referencing it are still pending.
Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure
all pending RCU callbacks (including gfs2_qd_dealloc) have completed
before the superblock is freed.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
crypto: nx - fix nx_crypto_ctx_exit argument
nx_crypto_ctx_shash_exit calls nx_crypto_ctx_exit with crypto_shash_ctx(...)
but crypto_shash_ctx gives a nx_crypto_ctx *, not a crypto_tfm *.
Fix the type in nx_crypto_ctx_exit and drop the bogus crypto_tfm_ctx
call.
This fixes the following oops:
BUG: Unable to handle kernel data access at 0xc0403effffffffc8
Faulting instruction address: 0xc000000000396cb4
Oops: Kernel access of bad area, sig: 11 [#15]
Call Trace:
nx_crypto_ctx_shash_exit+0x24/0x60
crypto_shash_exit_tfm+0x28/0x40
crypto_destroy_tfm+0x98/0x140
crypto_exit_ahash_using_shash+0x20/0x40
crypto_destroy_tfm+0x98/0x140
hash_release+0x1c/0x30
alg_sock_destruct+0x38/0x60
__sk_destruct+0x48/0x2b0
af_alg_release+0x58/0xb0
__sock_release+0x68/0x150
sock_close+0x20/0x40
__fput+0x110/0x3a0
sys_close+0x48/0xa0
system_call_exception+0x140/0x2d0
system_call_common+0xf4/0x258
.. which came from hardlink(1) opportunistically using AF_ALG.
The same problem exists with nx_crypto_ctx_skcipher_exit getting a context
it wasn't expecting, but apparently nobody hit that for years.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()
Drop a BUG_ON() that has been reachable since it was first added, way back
in 2009, and instead use get_unaligned() to perform potentially-unaligned
accesses.
For a given store, KVM x86's emulator tracks the entire value in the
destination operand, x86_emulate_ctxt.dst. If the destination is memory,
and the target splits multiple pages and/or is emulated MMIO, then KVM
handles each fragment independently. E.g. on a page split starting at page
offset 0xffc, KVM writes 4 bytes to the first page, then the remaining
bytes to the second page, using ctxt->dst as the source for both (with
appropriate offsets).
If the destination splits a page *and* hits emulated MMIO on the second
page, then KVM will complete the write to the first page, then emulate the
MMIO access to the second page. If there is a datamatch-enabled ioeventfd
at offset 0 of the second page, then KVM will process the remainder of the
store as a potential ioeventfd signal.
Putting it all together, if the guest emits a store that splits a page
starting at page offset N, and the second page has a datamatch-enabled
ioeventfd at offset 0, then KVM will check for datamatch using
&dst.valptr[N] as the source. Due to dst (and thus dst.valptr) being
32-byte aligned, if N is not aligned to @len, the BUG_ON() fires.
E.g. with a 16-byte store at page offset 0xffc, to an ioeventfd of len 8,
all initial checks in ioeventfd_in_range() will succeed, and the BUG_ON()
fires due to @val being 4-byte aligned, but not 8-byte aligned.
------------[ cut here ]------------
kernel BUG at arch/x86/kvm/../../../virt/kvm/eventfd.c:783!
Oops: invalid opcode: 0000 [#1] SMP
CPU: 0 UID: 1000 PID: 615 Comm: repro Not tainted 7.1.0-rc2-ff238429d1ea #365 PREEMPT
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:ioeventfd_write+0x6c/0x70 [kvm]
Call Trace:
<TASK>
__kvm_io_bus_write+0x85/0xb0 [kvm]
kvm_io_bus_write+0x53/0x80 [kvm]
vcpu_mmio_write+0x66/0xf0 [kvm]
emulator_read_write_onepage+0x12a/0x540 [kvm]
emulator_read_write+0x109/0x2b0 [kvm]
x86_emulate_insn+0x4f8/0xfb0 [kvm]
x86_emulate_instruction+0x181/0x790 [kvm]
kvm_mmu_page_fault+0x313/0x630 [kvm]
vmx_handle_exit+0x18a/0x590 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0xc81/0x1c90 [kvm]
kvm_vcpu_ioctl+0x2d5/0x970 [kvm]
__x64_sys_ioctl+0x8a/0xd0
do_syscall_64+0xb7/0x890
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f19c931a9bf
</TASK>
Modules linked in: kvm_intel kvm irqbypass
---[ end trace 0000000000000000 ]---
In a perfect world, the fix would be to simply delete the BUG_ON(), as KVM
x86 doesn't perform alignment checks on "normal" memory accesses at CPL0.
Sadly, C99 ruins all the fun; while the x86 architecture plays nice,
dereferencing an unaligned pointer directly is undefined behavior in C,
e.g. triggers splats when running with CONFIG_UBSAN_ALIGNMENT=y.
CVSS Score
7.1
EPSS Score
0.002
Published
2026-07-19
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