Linux: >> Linux Kernel >> 5.4.140 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
batman-adv: tt: avoid empty VLAN responses
The commit 16116dac2339 ("batman-adv: prevent TT request storms by not
sending inconsistent TT TLVLs") added checks to the local (direct) TT
response code. But the response can also be done indirectly by another node
using the global TT state. To avoid such inconsistency states reported in
the original fix, also avoid sending empty VLANs for replies from the
global TT state.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
batman-adv: tt: fix TOCTOU race for reported vlans
The local TT based TVLV is generated by first checking the number of VLANs
which have at least one TT entry. A new buffer with the correct size for
the VLANs is then allocated. Only then, the list of VLANs s used to fill
the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock
is held. But the actual number of TT entries of each VLAN can still
increase during this time - just not the number of VLANs in the list.
But the prefilter used in the buffer size calculation might still cause an
increase of the number of VLANs which need to be stored. Simply because a
VLAN might now suddenly have at least one entry when it had none in the
pre-alloc check - and then needs to occupy space which was not allocated.
It is better to overestimate the buffer size at the beginning and then fill
the buffer only with the VLANs which are not empty.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: cortina: Make RX SKB per-port
The SKB used to assemble packets from fragments in gmac_rx()
is static local, but the Gemini has two ethernet ports, meaning
there can be races between the ports on a bad day if a device
is using both.
Make the RX SKB a per-port variable and carry it over between
invocations in the port struct instead.
Zero the pointer once we call napi_gro_frags(), on error (after
calling napi_free_frags()) or if the port is stopped.
Zero it in some place where not strictly necessary just to
emphasize what is going on.
This was found by Sashiko during normal patch review.
CVSS Score
9.8
EPSS Score
0.006
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
When an sk_msg scatterlist ring wraps (sg.end < sg.start),
tls_push_record() chains the tail portion of the ring to the head
using sg_chain(). An extra entry in the sg array is reserved for
this:
struct sk_msg_sg {
[...]
/* The extra two elements:
* 1) used for chaining the front and sections when the list becomes
* partitioned (e.g. end < start). The crypto APIs require the
* chaining;
* 2) to chain tailer SG entries after the message.
*/
struct scatterlist data[MAX_MSG_FRAGS + 2];
The current code uses MAX_SKB_FRAGS + 1 as the ring size:
sg_chain(&msg_pl->sg.data[msg_pl->sg.start],
MAX_SKB_FRAGS - msg_pl->sg.start + 1,
msg_pl->sg.data);
This places the chain pointer at
sg_chain(data[start], (MAX_SKB_FRAGS - msg_start + 1) .. =
&data[start] + (MAX_SKB_FRAGS - msg_start + 1) - 1 =
data[start + (MAX_SKB_FRAGS - start + 1) - 1] =
data[MAX_SKB_FRAGS]
instead of the true last entry. This is likely due to a "race" of
the commit under Fixes landing close to
commit 031097d9e079 ("bpf: sk_msg, zap ingress queue on psock down")
Convert to ARRAY_SIZE and drop the data[start] / - start (as suggested
by Sabrina).
CVSS Score
9.8
EPSS Score
0.005
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: cortina: Carry over frag counter
The gmac_rx() NAPI poll function assembles packets in an
SKB from a ring buffer.
If the ring buffer gets completely emptied during a poll cycle,
we exit gmac_rx(), but the packet is not yet completely
assembled in the SKB, yet the fragment counter frag_nr is
reset to zero on the next invocation.
Solve this by making the RX fragment counter a part of the
port struct, and carry it over between invocations.
Reset the fragment counter only right after calling
napi_gro_frags(), on error (after calling napi_free_frags())
or if stopping the port.
Reset it in some place where not strictly necessary just to
emphasize what is going on.
This was found by Sashiko during normal patch review.
CVSS Score
9.8
EPSS Score
0.005
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
net: tls: prevent chain-after-chain in plain text SG
Sashiko points out that if end = 0 (start != 0) the current
code will create a chain link to content type right after
the wrap link:
This would create a chain where the wrap link points directly
to another chain link. The scatterlist API sg_next iterator
does not recursively resolve consecutive chain links.
meaning this is illegal input to crypto.
The wrapping link is unnecessary if end = 0. end is the entry after
the last one used so end = 0 means there's nothing pushed after
the wrap:
end start i
v v v
[ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap]
Skip the wrapping in this case.
TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0.
This avoids the chain-after-chain.
Move the wrap chaining before marking END and chaining off content
type, that feels like more logical ordering to me, but should not
matter from functional perspective.
CVSS Score
9.8
EPSS Score
0.005
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
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: reject oversized group bitmap descriptors
ocfs2_validate_gd_parent() only bounds bg_bits against the parent
allocator's chain geometry. A malicious descriptor can still claim a
bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in
the group descriptor block, so later bitmap scans and bit updates can run
past bg_bitmap.
Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent
allocator type and reject descriptors whose bg_size or bg_bits exceed that
capacity. Keep the existing chain geometry check so both the on-disk
bitmap layout and the allocator metadata must agree before the descriptor
is used.
Validation reproduced this kernel report:
KASAN use-after-free in _find_next_bit+0x7f/0xc0
Read of size 8
Call trace:
dump_stack_lvl+0x66/0xa0 (?:?)
print_report+0xd0/0x630 (?:?)
_find_next_bit+0x7f/0xc0 (?:?)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x188/0x2f0 (?:?)
kasan_report+0xe4/0x120 (?:?)
ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)
ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)
ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)
ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)
ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)
get_page_from_freelist+0x70e/0x2370 (?:?)
lock_release+0xc6/0x290 (?:?)
do_raw_spin_unlock+0x9a/0x100 (?:?)
kasan_unpoison+0x27/0x60 (?:?)
__bfs+0x147/0x240 (?:?)
get_page_from_freelist+0x83d/0x2370 (?:?)
ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)
sched_domains_numa_masks_clear+0x70/0xd0 (?:?)
check_irq_usage+0xe8/0xb70 (?:?)
__ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)
check_path+0x24/0x50 (?:?)
rcu_is_watching+0x20/0x50 (?:?)
check_prev_add+0xfd/0xd00 (?:?)
ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)
__folio_batch_add_and_move+0x1f5/0x3d0 (?:?)
ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)
filemap_add_folio+0x105/0x1f0 (?:?)
ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)
ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)
down_write+0xf5/0x180 (?:?)
ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)
__mark_inode_dirty+0x758/0x9a0 (?:?)
inode_to_bdi+0x41/0x90 (?:?)
balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)
generic_perform_write+0x252/0x440 (?:?)
mnt_put_write_access_file+0x16/0x70 (?:?)
file_update_time_flags+0xe4/0x200 (?:?)
ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)
lock_acquire+0x184/0x2f0 (?:?)
ksys_write+0xd2/0x170 (?:?)
apparmor_file_permission+0xf5/0x310 (?:?)
read_zero+0x8d/0x140 (?:?)
lock_is_held_type+0x8f/0x100 (?:?)
CVSS Score
8.8
EPSS Score
0.005
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
irqchip/imgpdc: Fix resource leak, add missing chained handler cleanup on remove
The driver allocates domain generic chips using
irq_alloc_domain_generic_chips() during probe and sets up chained
handlers using irq_set_chained_handler_and_data(). However, on driver
removal, the generic chips are not freed and the chained handlers are
not removed.
The generic chips remain on the global gc_list and may later be accessed by
generic interrupt chip suspend, resume, or shutdown callbacks after the
driver has been removed, potentially resulting in a use-after-free and
kernel crash.
The chained handlers that were installed in probe for peripheral and
syswake interrupts are also left dangling, which can lead to spurious
interrupts accessing freed memory.
Fix these issues by:
- Setting IRQ_DOMAIN_FLAG_DESTROY_GC flag in domain->flags, so the
core code automatically removes generic chips when irq_domain_remove()
is called
- Clearing all chained handlers with NULL in pdc_intc_remove()
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
pNFS: Fix use-after-free in pnfs_update_layout()
When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(),
the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds,
pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(),
which still references 'lo'. This results in a use-after-free when the
tracepoint accesses lo's fields.
Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).
CVSS Score
9.8
EPSS Score
0.005
Published
2026-07-19