medium 5.5

CVE-2024-35893 json

net/sched: act_skbmod: prevent kernel-infoleak

published 2024-05-19 2 y ago modified 2026-10-15 25 d ago also EUVD-2024-35611

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

syzbot found that tcf_skbmod_dump() was copying four bytes from kernel stack to user space [1].

The issue here is that 'struct tc_skbmod' has a four bytes hole.

We need to clear the structure before filling fields.

[1] BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline] BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline] BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline] BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 instrument_copy_to_user include/linux/instrumented.h:114 [inline] copy_to_user_iter lib/iov_iter.c:24 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 copy_to_iter include/linux/uio.h:196 [inline] simple_copy_to_iter net/core/datagram.c:532 [inline] __skb_datagram_iter+0x185/0x1000 net/core/datagram.c:420 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546 skb_copy_datagram_msg include/linux/skbuff.h:4050 [inline] netlink_recvmsg+0x432/0x1610 net/netlink/af_netlink.c:1962 sock_recvmsg_nosec net/socket.c:1046 [inline] sock_recvmsg+0x2c4/0x340 net/socket.c:1068 __sys_recvfrom+0x35a/0x5f0 net/socket.c:2242 __do_sys_recvfrom net/socket.c:2260 [inline] __se_sys_recvfrom net/socket.c:2256 [inline] __x64_sys_recvfrom+0x126/0x1d0 net/socket.c:2256 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was stored to memory at: pskb_expand_head+0x30f/0x19d0 net/core/skbuff.c:2253 netlink_trim+0x2c2/0x330 net/netlink/af_netlink.c:1317 netlink_unicast+0x9f/0x1260 net/netlink/af_netlink.c:1351 nlmsg_unicast include/net/netlink.h:1144 [inline] nlmsg_notify+0x21d/0x2f0 net/netlink/af_netlink.c:2610 rtnetlink_send+0x73/0x90 net/core/rtnetlink.c:741 rtnetlink_maybe_send include/linux/rtnetlink.h:17 [inline] tcf_add_notify net/sched/act_api.c:2048 [inline] tcf_action_add net/sched/act_api.c:2071 [inline] tc_ctl_action+0x146e/0x19d0 net/sched/act_api.c:2119 rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2559 rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6613 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0xf4c/0x1260 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x10df/0x11f0 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was stored to memory at: __nla_put lib/nlattr.c:1041 [inline] nla_put+0x1c6/0x230 lib/nlattr.c:1099 tcf_skbmod_dump+0x23f/0xc20 net/sched/act_skbmod.c:256 tcf_action_dump_old net/sched/act_api.c:1191 [inline] tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1227 tcf_action_dump+0x1fd/0x460 net/sched/act_api.c:1251 tca_get_fill+0x519/0x7a0 net/sched/act_api.c:1628 tcf_add_notify_msg net/sched/act_api.c:2023 [inline] tcf_add_notify net/sched/act_api.c:2042 [inline] tcf_action_add net/sched/act_api.c:2071 [inline] tc_ctl_action+0x1365/0x19d0 net/sched/act_api.c:2119 rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x375/0x650 net/netlink/af_netli ---truncated---

Patch / fix

fixed in 2 distros 6 links 8

Linux Linux 4.19.312, 5.4.274, 5.10.215, 5.15.154, 6.1.85, 6.6.26, 6.8.5, 6.9
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem V1.1.1

debian ubuntu red hat suse almalinux rocky linux

linux Debian 12 6.1.85-1
linux Debian 14, Debian 13 6.8.9-1

debian advisories DEBIAN-CVE-2024-35893

linux Ubuntu 20.04 LTS 5.4.0-189.209
linux Ubuntu 22.04 LTS 5.15.0-116.126
linux Ubuntu 24.04 LTS 6.8.0-38.38
linux-aws Ubuntu 20.04 LTS 5.4.0-1128.138
linux-aws Ubuntu 22.04 LTS 5.15.0-1065.71
linux-aws Ubuntu 24.04 LTS 6.8.0-1011.12
linux-gcp Ubuntu 20.04 LTS 5.4.0-1132.141
linux-gcp Ubuntu 22.04 LTS 5.15.0-1064.72

ubuntu advisories UBUNTU-CVE-2024-35893

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-rt RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-kvm RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-core RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-modules RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-debug-kvm RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-debug-core RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-debug-modules RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
kernel-rt-modules-extra RHEL 8 4.18.0-553.16.1.rt7.357.el8_10

red hat advisories RHSA-2024:5102 RHSA-2024:5101

kernel-rt Linux Micro 6.0 6.4.0-9.1
kernel-source-rt Linux Micro 6.0 6.4.0-9.1
kernel-source Linux Micro 6.0 6.4.0-18.1
kernel-default Linux Micro 6.0 6.4.0-18.1
kernel-kvmsmall Linux Micro 6.0 6.4.0-18.1
kernel-default-base Linux Micro 6.0 6.4.0-17.1.1.51
kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.5.1
kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.5.1

suse advisories SUSE-SU-2025:20028-1 SUSE-SU-2025:20008-1 SUSE-SU-2024:2973-1 SUSE-SU-2024:2947-1 SUSE-SU-2024:2940-1 SUSE-SU-2024:2939-1

kernel AlmaLinux 8 4.18.0-553.16.1.el8_10
perf AlmaLinux 8 4.18.0-553.16.1.el8_10
bpftool AlmaLinux 8 4.18.0-553.16.1.el8_10
kernel-core AlmaLinux 8 4.18.0-553.16.1.el8_10
kernel-tools AlmaLinux 8 4.18.0-553.16.1.el8_10
python3-perf AlmaLinux 8 4.18.0-553.16.1.el8_10
kernel-modules AlmaLinux 8 4.18.0-553.16.1.el8_10
kernel-zfcpdump AlmaLinux 8 4.18.0-553.16.1.el8_10

almalinux advisories ALSA-2024:5101 ALSA-2024:5102

kernel Rocky Linux 8 4.18.0-553.16.1.el8_10.cloud.0.1
kernel-rt Rocky Linux 8 4.18.0-553.16.1.rt7.357.el8_10
kernel Rocky Linux 8 4.18.0-553.16.1.el8_10

rocky linux advisories RXSA-2024:5101 RLSA-2024:5102 RLSA-2024:5101

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-35893 updated 2026-11-07 cvss 5.5

kernel: net/sched: act_skbmod: prevent kernel-infoleak

Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.16.1.el8_10, kernel 4.18.0-553.16.1.el8_10, bpftool 4.18.0-553.16.1.el8_10, kernel-core 4.18.0-553.16.1.el8_10, kernel-tools 4.18.0-553.16.1.el8_10, python3-perf 4.18.0-553.16.1.el8_10, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.16.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.16.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.16.1.el8_10
fixed: vendor fix RHSA-2024:5101
Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-kvm 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-kvm 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-core 4.18.0-553.16.1.rt7.357.el8_10, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules-extra 4.18.0-553.16.1.rt7.357.el8_10, +2 more
fixed: vendor fix RHSA-2024:5102
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-24-102-01 updated 2026-05-14 cvss 5.5

Siemens SIMATIC S7-1500 TM MFP

Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-05-23)

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Classification

Weakness

CWE-908 Use of Uninitialized Resource

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2024-35893
NVD CVE-2024-35893

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary