CVE-2024-35893

CVE-2024-35893 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbmod: prevent kernel-infoleak 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---

Frequently asked questions

What is CVE-2024-35893?
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbmod: prevent kernel-infoleak 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---
How severe is CVE-2024-35893?
CVE-2024-35893 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2024-35893 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-35893?
CVE-2024-35893 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-35893?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-35893 have an EU (EUVD) identifier?
Yes. CVE-2024-35893 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-35611.
When was CVE-2024-35893 published?
CVE-2024-35893 was published on 2024-05-19 and last updated on 2026-06-17.

References

Affected products (4)

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