CVE-2024-35893: net/sched: act_skbmod: prevent kernel-infoleak
First published: Sun May 19 2024(Updated: )
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---
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel | <4.19.312 | 4.19.312 |
| redhat/kernel | <5.4.274 | 5.4.274 |
| redhat/kernel | <5.10.215 | 5.10.215 |
| redhat/kernel | <5.15.154 | 5.15.154 |
| redhat/kernel | <6.1.85 | 6.1.85 |
| redhat/kernel | <6.6.26 | 6.6.26 |
| redhat/kernel | <6.8.5 | 6.8.5 |
| redhat/kernel | <6.9 | 6.9 |
| debian/linux | 5.10.223-1 6.1.106-3 6.1.99-1 6.10.6-1 6.10.9-1 |
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Reference Links
- https://git.kernel.org/stable/c/55d3fe7b2b7bc354e7cbc1f7b8f98a29ccd5a366
- https://git.kernel.org/stable/c/5e45dc4408857305f4685abfd7a528a1e58b51b5
- https://git.kernel.org/stable/c/729ad2ac2a2cdc9f4a4bdfd40bfd276e6bc33924
- https://git.kernel.org/stable/c/7bb2c7103d8c13b06a57bf997b8cdbe93cd7283c
- https://git.kernel.org/stable/c/a097fc199ab5f4b5392c5144034c0d2148b55a14
- https://git.kernel.org/stable/c/d313eb8b77557a6d5855f42d2234bd592c7b50dd
- https://git.kernel.org/stable/c/f190a4aa03cbd518bd9c62a66e1233984f5fd2ec
- https://git.kernel.org/stable/c/f356eb2fb567e0931143ac1769ac802d3b3e2077
- https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
- https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html
- https://launchpad.net/bugs/cve/CVE-2024-35893
- https://access.redhat.com/security/cve/CVE-2024-35893
- https://lore.kernel.org/linux-cve-announce/2024051949-CVE-2024-35893-5132@gregkh/T
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2281683
- https://access.redhat.com/errata/RHSA-2024:5102
- https://access.redhat.com/errata/RHSA-2024:5101
- https://bugzilla.redhat.com/show_bug.cgi?id=2281682
- https://git.kernel.org/linus/d313eb8b77557a6d5855f42d2234bd592c7b50dd
- https://security-tracker.debian.org/tracker/CVE-2024-35893
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-35893
- https://nvd.nist.gov/vuln/detail/CVE-2024-35893
- https://ubuntu.com/security/CVE-2024-35893
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