{"id":"CVE-2024-40958","summary":"netns: Make get_net_ns() handle zero refcount net","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetns: Make get_net_ns() handle zero refcount net\n\nSyzkaller hit a warning:\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 3 PID: 7890 at lib/refcount.c:25 refcount_warn_saturate+0xdf/0x1d0\nModules linked in:\nCPU: 3 PID: 7890 Comm: tun Not tainted 6.10.0-rc3-00100-gcaa4f9578aba-dirty #310\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xdf/0x1d0\nCode: 41 49 04 31 ff 89 de e8 9f 1e cd fe 84 db 75 9c e8 76 26 cd fe c6 05 b6 41 49 04 01 90 48 c7 c7 b8 8e 25 86 e8 d2 05 b5 fe 90 \u003c0f\u003e 0b 90 90 e9 79 ff ff ff e8 53 26 cd fe 0f b6 1\nRSP: 0018:ffff8881067b7da0 EFLAGS: 00010286\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff811c72ac\nRDX: ffff8881026a2140 RSI: ffffffff811c72b5 RDI: 0000000000000001\nRBP: ffff8881067b7db0 R08: 0000000000000000 R09: 205b5d3730353139\nR10: 0000000000000000 R11: 205d303938375420 R12: ffff8881086500c4\nR13: ffff8881086500c4 R14: ffff8881086500b0 R15: ffff888108650040\nFS:  00007f5b2961a4c0(0000) GS:ffff88823bd00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 000055d7ed36fd18 CR3: 00000001482f6000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n ? show_regs+0xa3/0xc0\n ? __warn+0xa5/0x1c0\n ? refcount_warn_saturate+0xdf/0x1d0\n ? report_bug+0x1fc/0x2d0\n ? refcount_warn_saturate+0xdf/0x1d0\n ? handle_bug+0xa1/0x110\n ? exc_invalid_op+0x3c/0xb0\n ? asm_exc_invalid_op+0x1f/0x30\n ? __warn_printk+0xcc/0x140\n ? __warn_printk+0xd5/0x140\n ? refcount_warn_saturate+0xdf/0x1d0\n get_net_ns+0xa4/0xc0\n ? __pfx_get_net_ns+0x10/0x10\n open_related_ns+0x5a/0x130\n __tun_chr_ioctl+0x1616/0x2370\n ? __sanitizer_cov_trace_switch+0x58/0xa0\n ? __sanitizer_cov_trace_const_cmp2+0x1c/0x30\n ? __pfx_tun_chr_ioctl+0x10/0x10\n tun_chr_ioctl+0x2f/0x40\n __x64_sys_ioctl+0x11b/0x160\n x64_sys_call+0x1211/0x20d0\n do_syscall_64+0x9e/0x1d0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f5b28f165d7\nCode: b3 66 90 48 8b 05 b1 48 2d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 8b 0d 81 48 2d 00 8\nRSP: 002b:00007ffc2b59c5e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5b28f165d7\nRDX: 0000000000000000 RSI: 00000000000054e3 RDI: 0000000000000003\nRBP: 00007ffc2b59c650 R08: 00007f5b291ed8c0 R09: 00007f5b2961a4c0\nR10: 0000000029690010 R11: 0000000000000246 R12: 0000000000400730\nR13: 00007ffc2b59cf40 R14: 0000000000000000 R15: 0000000000000000\n \u003c/TASK\u003e\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nThis is trigger as below:\n          ns0                                    ns1\ntun_set_iff() //dev is tun0\n   tun-\u003edev = dev\n//ip link set tun0 netns ns1\n                                       put_net() //ref is 0\n__tun_chr_ioctl() //TUNGETDEVNETNS\n   net = dev_net(tun-\u003edev);\n   open_related_ns(&net-\u003ens, get_net_ns); //ns1\n     get_net_ns()\n        get_net() //addition on 0\n\nUse maybe_get_net() in get_net_ns in case net's ref is zero to fix this","modified":"2026-05-07T04:15:53.819783Z","published":"2024-07-12T12:32:00.431Z","related":["ALSA-2024:5363","ALSA-2024:7000","ALSA-2024:7001","SUSE-SU-2024:2894-1","SUSE-SU-2024:2939-1","SUSE-SU-2024:2947-1","SUSE-SU-2024:3194-1","SUSE-SU-2024:3195-1","SUSE-SU-2024:3383-1","SUSE-SU-2025:20044-1","SUSE-SU-2025:20047-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/40xxx/CVE-2024-40958.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1b631bffcb2c09551888f3c723f4365c91fe05ef"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2b82028a1f5ee3a8e04090776b10c534144ae77b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3a6cd326ead7c8bb1f64486789a01974a9f1ad55"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3af28df0d883e8c89a29ac31bc65f9023485743b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb7f811f638a14590ff98f53c6dd1fb54627d940"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ef0394ca25953ea0eddcc82feae1f750451f1876"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff960f9d3edbe08a736b5a224d91a305ccc946b0"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/40xxx/CVE-2024-40958.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-40958"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f"},{"fixed":"3a6cd326ead7c8bb1f64486789a01974a9f1ad55"},{"fixed":"2b82028a1f5ee3a8e04090776b10c534144ae77b"},{"fixed":"cb7f811f638a14590ff98f53c6dd1fb54627d940"},{"fixed":"1b631bffcb2c09551888f3c723f4365c91fe05ef"},{"fixed":"ef0394ca25953ea0eddcc82feae1f750451f1876"},{"fixed":"3af28df0d883e8c89a29ac31bc65f9023485743b"},{"fixed":"ff960f9d3edbe08a736b5a224d91a305ccc946b0"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-40958.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.2.0"},{"fixed":"5.4.279"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.162"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.9.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-40958.json"}}],"schema_version":"1.7.5"}