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

net: sched: fix memory leak in tcindex_set_parms

Syzkaller reports a memory leak as follows:
====================================
BUG: memory leak
unreferenced object 0xffff88810c287f00 (size 256):
comm "syz-executor105", pid 3600, jiffies 4294943292 (age 12.990s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff814cf9f0>] kmalloc_trace+0x20/0x90 mm/slab_common.c:1046
[<ffffffff839c9e07>] kmalloc include/linux/slab.h:576 [inline]
[<ffffffff839c9e07>] kmalloc_array include/linux/slab.h:627 [inline]
[<ffffffff839c9e07>] kcalloc include/linux/slab.h:659 [inline]
[<ffffffff839c9e07>] tcf_exts_init include/net/pkt_cls.h:250 [inline]
[<ffffffff839c9e07>] tcindex_set_parms+0xa7/0xbe0 net/sched/cls_tcindex.c:342
[<ffffffff839caa1f>] tcindex_change+0xdf/0x120 net/sched/cls_tcindex.c:553
[<ffffffff8394db62>] tc_new_tfilter+0x4f2/0x1100 net/sched/cls_api.c:2147
[<ffffffff8389e91c>] rtnetlink_rcv_msg+0x4dc/0x5d0 net/core/rtnetlink.c:6082
[<ffffffff839eba67>] netlink_rcv_skb+0x87/0x1d0 net/netlink/af_netlink.c:2540
[<ffffffff839eab87>] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
[<ffffffff839eab87>] netlink_unicast+0x397/0x4c0 net/netlink/af_netlink.c:1345
[<ffffffff839eb046>] netlink_sendmsg+0x396/0x710 net/netlink/af_netlink.c:1921
[<ffffffff8383e796>] sock_sendmsg_nosec net/socket.c:714 [inline]
[<ffffffff8383e796>] sock_sendmsg+0x56/0x80 net/socket.c:734
[<ffffffff8383eb08>] ____sys_sendmsg+0x178/0x410 net/socket.c:2482
[<ffffffff83843678>] ___sys_sendmsg+0xa8/0x110 net/socket.c:2536
[<ffffffff838439c5>] __sys_sendmmsg+0x105/0x330 net/socket.c:2622
[<ffffffff83843c14>] __do_sys_sendmmsg net/socket.c:2651 [inline]
[<ffffffff83843c14>] __se_sys_sendmmsg net/socket.c:2648 [inline]
[<ffffffff83843c14>] __x64_sys_sendmmsg+0x24/0x30 net/socket.c:2648
[<ffffffff84605fd5>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff84605fd5>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84800087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
====================================

Kernel uses tcindex_change() to change an existing
filter properties.

Yet the problem is that, during the process of changing,
if `old_r` is retrieved from `p->perfect`, then
kernel uses tcindex_alloc_perfect_hash() to newly
allocate filter results, uses tcindex_filter_result_init()
to clear the old filter result, without destroying
its tcf_exts structure, which triggers the above memory leak.

To be more specific, there are only two source for the `old_r`,
according to the tcindex_lookup(). `old_r` is retrieved from
`p->perfect`, or `old_r` is retrieved from `p->h`.

* If `old_r` is retrieved from `p->perfect`, kernel uses
tcindex_alloc_perfect_hash() to newly allocate the
filter results. Then `r` is assigned with `cp->perfect + handle`,
which is newly allocated. So condition `old_r && old_r != r` is
true in this situation, and kernel uses tcindex_filter_result_init()
to clear the old filter result, without destroying
its tcf_exts structure

* If `old_r` is retrieved from `p->h`, then `p->perfect` is NULL
according to the tcindex_lookup(). Considering that `cp->h`
is directly copied from `p->h` and `p->perfect` is NULL,
`r` is assigned with `tcindex_lookup(cp, handle)`, whose value
should be the same as `old_r`, so condition `old_r && old_r != r`
is false in this situation, kernel ignores using
tcindex_filter_result_init() to clear the old filter result.

So only when `old_r` is retrieved from `p->perfect` does kernel use
tcindex_filter_result_init() to clear the old filter result, which
triggers the above memory leak.

Considering that there already exists a tc_filter_wq workqueue
to destroy the old tcindex_d
---truncated---
Published: 2025-09-18
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2025-29973 In the Linux kernel, the following vulnerability has been resolved: net: sched: fix memory leak in tcindex_set_parms Syzkaller reports a memory leak as follows: ==================================== BUG: memory leak unreferenced object 0xffff88810c287f00 (size 256): comm "syz-executor105", pid 3600, jiffies 4294943292 (age 12.990s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff814cf9f0>] kmalloc_trace+0x20/0x90 mm/slab_common.c:1046 [<ffffffff839c9e07>] kmalloc include/linux/slab.h:576 [inline] [<ffffffff839c9e07>] kmalloc_array include/linux/slab.h:627 [inline] [<ffffffff839c9e07>] kcalloc include/linux/slab.h:659 [inline] [<ffffffff839c9e07>] tcf_exts_init include/net/pkt_cls.h:250 [inline] [<ffffffff839c9e07>] tcindex_set_parms+0xa7/0xbe0 net/sched/cls_tcindex.c:342 [<ffffffff839caa1f>] tcindex_change+0xdf/0x120 net/sched/cls_tcindex.c:553 [<ffffffff8394db62>] tc_new_tfilter+0x4f2/0x1100 net/sched/cls_api.c:2147 [<ffffffff8389e91c>] rtnetlink_rcv_msg+0x4dc/0x5d0 net/core/rtnetlink.c:6082 [<ffffffff839eba67>] netlink_rcv_skb+0x87/0x1d0 net/netlink/af_netlink.c:2540 [<ffffffff839eab87>] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] [<ffffffff839eab87>] netlink_unicast+0x397/0x4c0 net/netlink/af_netlink.c:1345 [<ffffffff839eb046>] netlink_sendmsg+0x396/0x710 net/netlink/af_netlink.c:1921 [<ffffffff8383e796>] sock_sendmsg_nosec net/socket.c:714 [inline] [<ffffffff8383e796>] sock_sendmsg+0x56/0x80 net/socket.c:734 [<ffffffff8383eb08>] ____sys_sendmsg+0x178/0x410 net/socket.c:2482 [<ffffffff83843678>] ___sys_sendmsg+0xa8/0x110 net/socket.c:2536 [<ffffffff838439c5>] __sys_sendmmsg+0x105/0x330 net/socket.c:2622 [<ffffffff83843c14>] __do_sys_sendmmsg net/socket.c:2651 [inline] [<ffffffff83843c14>] __se_sys_sendmmsg net/socket.c:2648 [inline] [<ffffffff83843c14>] __x64_sys_sendmmsg+0x24/0x30 net/socket.c:2648 [<ffffffff84605fd5>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<ffffffff84605fd5>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [<ffffffff84800087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd ==================================== Kernel uses tcindex_change() to change an existing filter properties. Yet the problem is that, during the process of changing, if `old_r` is retrieved from `p->perfect`, then kernel uses tcindex_alloc_perfect_hash() to newly allocate filter results, uses tcindex_filter_result_init() to clear the old filter result, without destroying its tcf_exts structure, which triggers the above memory leak. To be more specific, there are only two source for the `old_r`, according to the tcindex_lookup(). `old_r` is retrieved from `p->perfect`, or `old_r` is retrieved from `p->h`. * If `old_r` is retrieved from `p->perfect`, kernel uses tcindex_alloc_perfect_hash() to newly allocate the filter results. Then `r` is assigned with `cp->perfect + handle`, which is newly allocated. So condition `old_r && old_r != r` is true in this situation, and kernel uses tcindex_filter_result_init() to clear the old filter result, without destroying its tcf_exts structure * If `old_r` is retrieved from `p->h`, then `p->perfect` is NULL according to the tcindex_lookup(). Considering that `cp->h` is directly copied from `p->h` and `p->perfect` is NULL, `r` is assigned with `tcindex_lookup(cp, handle)`, whose value should be the same as `old_r`, so condition `old_r && old_r != r` is false in this situation, kernel ignores using tcindex_filter_result_init() to clear the old filter result. So only when `old_r` is retrieved from `p->perfect` does kernel use tcindex_filter_result_init() to clear the old filter result, which triggers the above memory leak. Considering that there already exists a tc_filter_wq workqueue to destroy the old tcindex_d ---truncated---
History

Wed, 14 Jan 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 11 Dec 2025 20:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Mon, 29 Sep 2025 11:30:00 +0000

Type Values Removed Values Added
References

Fri, 19 Sep 2025 09:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Fri, 19 Sep 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Thu, 18 Sep 2025 13:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: sched: fix memory leak in tcindex_set_parms Syzkaller reports a memory leak as follows: ==================================== BUG: memory leak unreferenced object 0xffff88810c287f00 (size 256): comm "syz-executor105", pid 3600, jiffies 4294943292 (age 12.990s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff814cf9f0>] kmalloc_trace+0x20/0x90 mm/slab_common.c:1046 [<ffffffff839c9e07>] kmalloc include/linux/slab.h:576 [inline] [<ffffffff839c9e07>] kmalloc_array include/linux/slab.h:627 [inline] [<ffffffff839c9e07>] kcalloc include/linux/slab.h:659 [inline] [<ffffffff839c9e07>] tcf_exts_init include/net/pkt_cls.h:250 [inline] [<ffffffff839c9e07>] tcindex_set_parms+0xa7/0xbe0 net/sched/cls_tcindex.c:342 [<ffffffff839caa1f>] tcindex_change+0xdf/0x120 net/sched/cls_tcindex.c:553 [<ffffffff8394db62>] tc_new_tfilter+0x4f2/0x1100 net/sched/cls_api.c:2147 [<ffffffff8389e91c>] rtnetlink_rcv_msg+0x4dc/0x5d0 net/core/rtnetlink.c:6082 [<ffffffff839eba67>] netlink_rcv_skb+0x87/0x1d0 net/netlink/af_netlink.c:2540 [<ffffffff839eab87>] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] [<ffffffff839eab87>] netlink_unicast+0x397/0x4c0 net/netlink/af_netlink.c:1345 [<ffffffff839eb046>] netlink_sendmsg+0x396/0x710 net/netlink/af_netlink.c:1921 [<ffffffff8383e796>] sock_sendmsg_nosec net/socket.c:714 [inline] [<ffffffff8383e796>] sock_sendmsg+0x56/0x80 net/socket.c:734 [<ffffffff8383eb08>] ____sys_sendmsg+0x178/0x410 net/socket.c:2482 [<ffffffff83843678>] ___sys_sendmsg+0xa8/0x110 net/socket.c:2536 [<ffffffff838439c5>] __sys_sendmmsg+0x105/0x330 net/socket.c:2622 [<ffffffff83843c14>] __do_sys_sendmmsg net/socket.c:2651 [inline] [<ffffffff83843c14>] __se_sys_sendmmsg net/socket.c:2648 [inline] [<ffffffff83843c14>] __x64_sys_sendmmsg+0x24/0x30 net/socket.c:2648 [<ffffffff84605fd5>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<ffffffff84605fd5>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [<ffffffff84800087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd ==================================== Kernel uses tcindex_change() to change an existing filter properties. Yet the problem is that, during the process of changing, if `old_r` is retrieved from `p->perfect`, then kernel uses tcindex_alloc_perfect_hash() to newly allocate filter results, uses tcindex_filter_result_init() to clear the old filter result, without destroying its tcf_exts structure, which triggers the above memory leak. To be more specific, there are only two source for the `old_r`, according to the tcindex_lookup(). `old_r` is retrieved from `p->perfect`, or `old_r` is retrieved from `p->h`. * If `old_r` is retrieved from `p->perfect`, kernel uses tcindex_alloc_perfect_hash() to newly allocate the filter results. Then `r` is assigned with `cp->perfect + handle`, which is newly allocated. So condition `old_r && old_r != r` is true in this situation, and kernel uses tcindex_filter_result_init() to clear the old filter result, without destroying its tcf_exts structure * If `old_r` is retrieved from `p->h`, then `p->perfect` is NULL according to the tcindex_lookup(). Considering that `cp->h` is directly copied from `p->h` and `p->perfect` is NULL, `r` is assigned with `tcindex_lookup(cp, handle)`, whose value should be the same as `old_r`, so condition `old_r && old_r != r` is false in this situation, kernel ignores using tcindex_filter_result_init() to clear the old filter result. So only when `old_r` is retrieved from `p->perfect` does kernel use tcindex_filter_result_init() to clear the old filter result, which triggers the above memory leak. Considering that there already exists a tc_filter_wq workqueue to destroy the old tcindex_d ---truncated---
Title net: sched: fix memory leak in tcindex_set_parms
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T19:18:43.526Z

Reserved: 2025-09-17T14:53:06.998Z

Link: CVE-2022-50396

cve-icon Vulnrichment

Updated: 2026-01-14T18:51:50.361Z

cve-icon NVD

Status : Modified

Published: 2025-09-18T14:15:38.737

Modified: 2026-01-14T19:16:15.120

Link: CVE-2022-50396

cve-icon Redhat

Severity : Important

Publid Date: 2025-09-18T00:00:00Z

Links: CVE-2022-50396 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-09-19T09:36:38Z

Weaknesses