CVE-2023-52977

Published Mar 27, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix flow memory leak in ovs_flow_cmd_new Syzkaller reports a memory leak of new_flow in ovs_flow_cmd_new() as it is not freed when an allocation of a key fails. BUG: memory leak unreferenced object 0xffff888116668000 (size 632): comm "syz-executor231", pid 1090, jiffies 4294844701 (age 18.871s) 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: [<00000000defa3494>] kmem_cache_zalloc include/linux/slab.h:654 [inline] [<00000000defa3494>] ovs_flow_alloc+0x19/0x180 net/openvswitch/flow_table.c:77 [<00000000c67d8873>] ovs_flow_cmd_new+0x1de/0xd40 net/openvswitch/datapath.c:957 [<0000000010a539a8>] genl_family_rcv_msg_doit+0x22d/0x330 net/netlink/genetlink.c:739 [<00000000dff3302d>] genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] [<00000000dff3302d>] genl_rcv_msg+0x328/0x590 net/netlink/genetlink.c:800 [<000000000286dd87>] netlink_rcv_skb+0x153/0x430 net/netlink/af_netlink.c:2515 [<0000000061fed410>] genl_rcv+0x24/0x40 net/netlink/genetlink.c:811 [<000000009dc0f111>] netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] [<000000009dc0f111>] netlink_unicast+0x545/0x7f0 net/netlink/af_netlink.c:1339 [<000000004a5ee816>] netlink_sendmsg+0x8e7/0xde0 net/netlink/af_netlink.c:1934 [<00000000482b476f>] sock_sendmsg_nosec net/socket.c:651 [inline] [<00000000482b476f>] sock_sendmsg+0x152/0x190 net/socket.c:671 [<00000000698574ba>] ____sys_sendmsg+0x70a/0x870 net/socket.c:2356 [<00000000d28d9e11>] ___sys_sendmsg+0xf3/0x170 net/socket.c:2410 [<0000000083ba9120>] __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 [<00000000c00628f8>] do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 [<000000004abfdcf4>] entry_SYSCALL_64_after_hwframe+0x61/0xc6 To fix this the patch rearranges the goto labels to reflect the order of object allocations and adds appropriate goto statements on the error paths. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
CWE-401
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-401

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: cgroup: Avoid iteration of dying tasks with zero refcount The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") extended the lifetime of tasks on the dying_tasks list. The iterators have provision to go through dying_tasks because of dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however, it was expected that such tasks can obtain a new reference (that is possible before cgroup_task_release()/put_task_struct_rcu_user()). The tasks after cgroup_task_release() and before cgroup_task_free() are subject to race when they may or may not have ->usage count > 0. The race window is between css_task_iter_next() invocations when css_set_lock is released and we may arrive at a new ->task_pos. The iterator should not attempt to resurrect tasks whose ->usage count dropped to zero. (When that happens, __put_task_struct_rcu_cb() is already imminent and the returned task_struct would could be used after free.) As for the fix, we cannot simply check the signal->live count of a task on the dying list because that won't distinguish regular zombies waiting to be reaped from RCU remnant tasks that are going to be free'd. Therefore add an extra check to rule out ->usage==0 tasks from any iteration. The repeat: loop in css_task_iter_advance() doesn't consider ->usage count, so add a new loop to css_task_iter_next() to skip de-used tasks on the dying_list. Rough illustration of the possible race R (reader of cgroup.procs) T (thread) L (group leader) --------------------------------- -------------------------------- -------------------------------- L exits, signal->live > 0 cgroup_task_dead(L) css_set_skip_task_iters() // skips only cset->tasks list_add_tail(&L->cg_list, &cset->dying_tasks) css_task_iter_next() take css_set_lock css_task_iter_advance() leader && signal->live != 0 => it->task_pos = &L->cg_list release css_set_lock T exits --signal->live == 0 cgroup_task_dead(T) // css_set_lock release_task(T) cgroup_task_release(T) release_task(L) // zap_leader cgroup_task_release(L) put_task_struct_rcu_user(L) ...RCU... put_task_struct(L) L->usage = 0 /* L still on dying_tasks */ ...RCU... __put_task_struct(L) css_task_iter_next() // another iteration take css_set_lock it->task_pos = &L->cg_list get_task_struct(L) => addition on 0 drop css_set_lock cgroup_task_free(L) css_set_skip_task_iters() // dying skip comes too late free_task(L) cgroup_procs_show() task_pid_vnr(L)•CVE-2026-98163