GHSA-3PPH-X43C-2V7F
Vulnerability from github – Published: 2024-08-26 12:31 – Updated: 2025-11-04 00:31In the Linux kernel, the following vulnerability has been resolved:
net: bridge: mcast: wait for previous gc cycles when removing port
syzbot hit a use-after-free[1] which is caused because the bridge doesn't make sure that all previous garbage has been collected when removing a port. What happens is: CPU 1 CPU 2 start gc cycle remove port acquire gc lock first wait for lock call br_multicasg_gc() directly acquire lock now but free port the port can be freed while grp timers still running
Make sure all previous gc cycles have finished by using flush_work before freeing the port.
[1] BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699
CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417 __run_timer_base kernel/time/timer.c:2428 [inline] __run_timer_base kernel/time/timer.c:2421 [inline] run_timer_base+0x111/0x190 kernel/time/timer.c:2437
{
"affected": [],
"aliases": [
"CVE-2024-44934"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-26T11:15:05Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mcast: wait for previous gc cycles when removing port\n\nsyzbot hit a use-after-free[1] which is caused because the bridge doesn\u0027t\nmake sure that all previous garbage has been collected when removing a\nport. What happens is:\n CPU 1 CPU 2\n start gc cycle remove port\n acquire gc lock first\n wait for lock\n call br_multicasg_gc() directly\n acquire lock now but free port\n the port can be freed\n while grp timers still\n running\n\nMake sure all previous gc cycles have finished by using flush_work before\nfreeing the port.\n\n[1]\n BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861\n Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699\n\n CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0\n Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024\n Call Trace:\n \u003cIRQ\u003e\n __dump_stack lib/dump_stack.c:88 [inline]\n dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114\n print_address_description mm/kasan/report.c:377 [inline]\n print_report+0xc3/0x620 mm/kasan/report.c:488\n kasan_report+0xd9/0x110 mm/kasan/report.c:601\n br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861\n call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792\n expire_timers kernel/time/timer.c:1843 [inline]\n __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417\n __run_timer_base kernel/time/timer.c:2428 [inline]\n __run_timer_base kernel/time/timer.c:2421 [inline]\n run_timer_base+0x111/0x190 kernel/time/timer.c:2437",
"id": "GHSA-3pph-x43c-2v7f",
"modified": "2025-11-04T00:31:18Z",
"published": "2024-08-26T12:31:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-44934"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0d8b26e10e680c01522d7cc14abe04c3265a928f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1e16828020c674b3be85f52685e8b80f9008f50f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/92c4ee25208d0f35dafc3213cdf355fbe449e078"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b2f794b168cf560682ff976b255aa6d29d14a658"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e3145ca904fa8dbfd1a5bf0187905bc117b0efce"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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