Linux: >> Linux Kernel >> 4.9.29 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
openvswitch: cap upcall PID array size and pre-size vport replies
The vport netlink reply helpers allocate a fixed-size skb with
nlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID
array via ovs_vport_get_upcall_portids(). Since
ovs_vport_set_upcall_portids() accepts any non-zero multiple of
sizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID
array large enough to overflow the reply buffer, causing nla_put() to
fail with -EMSGSIZE and hitting BUG_ON(err < 0). On systems with
unprivileged user namespaces enabled (e.g., Ubuntu default), this is
reachable via unshare -Urn since OVS vport mutation operations use
GENL_UNS_ADMIN_PERM.
kernel BUG at net/openvswitch/datapath.c:2414!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1
RIP: 0010:ovs_vport_cmd_set+0x34c/0x400
Call Trace:
<TASK>
genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116)
genl_rcv_msg (net/netlink/genetlink.c:1194)
netlink_rcv_skb (net/netlink/af_netlink.c:2550)
genl_rcv (net/netlink/genetlink.c:1219)
netlink_unicast (net/netlink/af_netlink.c:1344)
netlink_sendmsg (net/netlink/af_netlink.c:1894)
__sys_sendto (net/socket.c:2206)
__x64_sys_sendto (net/socket.c:2209)
do_syscall_64 (arch/x86/entry/syscall_64.c:63)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
</TASK>
Kernel panic - not syncing: Fatal exception
Reject attempts to set more PIDs than nr_cpu_ids in
ovs_vport_set_upcall_portids(), and pre-compute the worst-case reply
size in ovs_vport_cmd_msg_size() based on that bound, similar to the
existing ovs_dp_cmd_msg_size(). nr_cpu_ids matches the cap already
used by the per-CPU dispatch configuration on the datapath side
(ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the
two sides stay consistent.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO
nf_osf_match_one() computes ctx->window % f->wss.val in the
OSF_WSS_MODULO branch with no guard for f->wss.val == 0. A
CAP_NET_ADMIN user can add such a fingerprint via nfnetlink; a
subsequent matching TCP SYN divides by zero and panics the kernel.
Reject the bogus fingerprint in nfnl_osf_add_callback() above the
per-option for-loop. f->wss is per-fingerprint, not per-option, so
the check must run regardless of f->opt_num (including 0). Also
reject wss.wc >= OSF_WSS_MAX; nf_osf_match_one() already treats that
as "should not happen".
Crash:
Oops: divide error: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)
Call Trace:
<IRQ>
nf_osf_match (net/netfilter/nfnetlink_osf.c:220)
xt_osf_match_packet (net/netfilter/xt_osf.c:32)
ipt_do_table (net/ipv4/netfilter/ip_tables.c:348)
nf_hook_slow (net/netfilter/core.c:622)
ip_local_deliver (net/ipv4/ip_input.c:265)
ip_rcv (include/linux/skbuff.h:1162)
__netif_receive_skb_one_core (net/core/dev.c:6181)
process_backlog (net/core/dev.c:6642)
__napi_poll (net/core/dev.c:7710)
net_rx_action (net/core/dev.c:7945)
handle_softirqs (kernel/softirq.c:622)
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
slip: reject VJ receive packets on instances with no rstate array
slhc_init() accepts rslots == 0 as a valid configuration, with the
documented meaning of 'no receive compression'. In that case the
allocation loop in slhc_init() is skipped, so comp->rstate stays
NULL and comp->rslot_limit stays 0 (from the kzalloc of struct
slcompress).
The receive helpers do not defend against that configuration.
slhc_uncompress() dereferences comp->rstate[x] when the VJ header
carries an explicit connection ID, and slhc_remember() later assigns
cs = &comp->rstate[...] after only comparing the packet's slot number
to comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the
range check, and the code dereferences a NULL rstate.
The configuration is reachable in-tree through PPP. PPPIOCSMAXCID
stores its argument in a signed int, and (val >> 16) uses arithmetic
shift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1
is 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because
/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path
is reachable from an unprivileged user namespace. Once the malformed
VJ state is installed, any inbound VJ-compressed or VJ-uncompressed
frame that selects slot 0 crashes the kernel in softirq context:
Oops: general protection fault, probably for non-canonical
address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)
Call Trace:
<TASK>
ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)
ppp_input (drivers/net/ppp/ppp_generic.c:2359)
ppp_async_process (drivers/net/ppp/ppp_async.c:492)
tasklet_action_common (kernel/softirq.c:926)
handle_softirqs (kernel/softirq.c:623)
run_ksoftirqd (kernel/softirq.c:1055)
smpboot_thread_fn (kernel/smpboot.c:160)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:164)
</TASK>
Reject the receive side on such instances instead of touching rstate.
slhc_uncompress() falls through to its existing 'bad' label, which
bumps sls_i_error and enters the toss state. slhc_remember() mirrors
that with an explicit sls_i_error increment followed by slhc_toss();
the sls_i_runt counter is not used here because a missing rstate is
an internal configuration state, not a runt packet.
The transmit path is unaffected: the only in-tree caller that picks
rslots from userspace (ppp_generic.c) still supplies tslots >= 1, and
slip.c always calls slhc_init(16, 16), so comp->tstate remains valid
and slhc_compress() continues to work.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
slip: bound decode() reads against the compressed packet length
slhc_uncompress() parses a VJ-compressed TCP header by advancing a
pointer through the packet via decode() and pull16(). Neither helper
bounds-checks against isize, and decode() masks its return with
& 0xffff so it can never return the -1 that callers test for -- those
error paths are dead code.
A short compressed frame whose change byte requests optional fields
lets decode() read past the end of the packet. The over-read bytes
are folded into the cached cstate and reflected into subsequent
reconstructed packets.
Make decode() and pull16() take the packet end pointer and return -1
when exhausted. Add a bounds check before the TCP-checksum read.
The existing == -1 tests now do what they were always meant to.
CVSS Score
8.2
EPSS Score
0.003
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
netfilter: arp_tables: fix IEEE1394 ARP payload parsing
Weiming Shi says:
"arp_packet_match() unconditionally parses the ARP payload assuming two
hardware addresses are present (source and target). However,
IPv4-over-IEEE1394 ARP (RFC 2734) omits the target hardware address
field, and arp_hdr_len() already accounts for this by returning a
shorter length for ARPHRD_IEEE1394 devices.
As a result, on IEEE1394 interfaces arp_packet_match() advances past a
nonexistent target hardware address and reads the wrong bytes for both
the target device address comparison and the target IP address. This
causes arptables rules to match against garbage data, leading to
incorrect filtering decisions: packets that should be accepted may be
dropped and vice versa.
The ARP stack in net/ipv4/arp.c (arp_create and arp_process) already
handles this correctly by skipping the target hardware address for
ARPHRD_IEEE1394. Apply the same pattern to arp_packet_match()."
Mangle the original patch to always return 0 (no match) in case user
matches on the target hardware address which is never present in
IEEE1394.
Note that this returns 0 (no match) for either normal and inverse match
because matching in the target hardware address in ARPHRD_IEEE1394 has
never been supported by arptables. This is intentional, matching on the
target hardware address should never evaluate true for ARPHRD_IEEE1394.
Moreover, adjust arpt_mangle to drop the packet too as AI suggests:
In arpt_mangle, the logic assumes a standard ARP layout. Because
IEEE1394 (FireWire) omits the target hardware address, the linear
pointer arithmetic miscalculates the offset for the target IP address.
This causes mangling operations to write to the wrong location, leading
to packet corruption. To ensure safety, this patch drops packets
(NF_DROP) when mangling is requested for these fields on IEEE1394
devices, as the current implementation cannot correctly map the FireWire
ARP payload.
This omits both mangling target hardware and IP address. Even if IP
address mangling should be possible in IEEE1394, this would require
to adjust arpt_mangle offset calculation, which has never been
supported.
Based on patch from Weiming Shi <bestswngs@gmail.com>.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_get_sndtimeo_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_state_change_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_new_connection_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: propagate shared-frag marker through frag-transfer helpers
Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail
to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when
moving frags from source to destination. __pskb_copy_fclone() defers
the rest of the shinfo metadata to skb_copy_header() after copying
frag descriptors, but that helper only carries over gso_{size,segs,
type} and never touches skb_shinfo()->flags; skb_shift() moves frag
descriptors directly and leaves flags untouched. As a result, the
destination skb keeps a reference to the same externally-owned or
page-cache-backed pages while reporting skb_has_shared_frag() as
false.
The mismatch is harmful in any in-place writer that uses
skb_has_shared_frag() to decide whether shared pages must be detoured
through skb_cow_data(). ESP input is one such writer (esp4.c,
esp6.c), and a single nft 'dup to <local>' rule -- or any other
nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d
skb in esp_input() with the marker stripped, letting an unprivileged
user write into the page cache of a root-owned read-only file via
authencesn-ESN stray writes.
Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors
were actually moved from the source. skb_copy() and skb_copy_expand()
share skb_copy_header() too but linearize all paged data into freshly
allocated head storage and emerge with nr_frags == 0, so
skb_has_shared_frag() returns false on its own; they need no change.
The same omission exists in skb_gro_receive() and skb_gro_receive_list().
The former moves the incoming skb's frag descriptors into the
accumulator's last sub-skb via two paths (a direct frag-move loop and
the head_frag + memcpy path); the latter chains the incoming skb whole
onto p's frag_list. Downstream skb_segment() reads only
skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's
shinfo as the nskb -- both p and lp must carry the marker.
The same omission also exists in tcp_clone_payload(), which builds an
MTU probe skb by moving frag descriptors from skbs on sk_write_queue
into a freshly allocated nskb. The helper falls into the same family
and warrants the same fix for consistency; no TCP TX-side in-place
writer is currently known to reach a user page through this gap, but
a future consumer depending on the marker would regress silently.
The same omission exists in skb_segment(): the per-iteration flag
merge takes only head_skb's flag, and the inner switch that rebinds
frag_skb to list_skb on head_skb-frags exhaustion does not fold the
new frag_skb's flag into nskb. Fold frag_skb's flag at both sites
so segments drawing frags from frag_list members carry the marker.
CVSS Score
8.8
EPSS Score
0.001
Published
2026-05-23
In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: preserve shared-frag marker during coalescing
skb_try_coalesce() can attach paged frags from @from to @to. If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.
That breaks the invariant relied on by later in-place writers. In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.
Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags. The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.
CVSS Score
7.8
EPSS Score
0.037
Published
2026-05-23