GHSA-Q6H5-3VM3-9H46
Vulnerability from github – Published: 2024-05-22 09:31 – Updated: 2025-09-24 03:30In the Linux kernel, the following vulnerability has been resolved:
netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value
Currently, when the rule related to IDLETIMER is added, idletimer_tg timer structure is initialized by kmalloc on executing idletimer_tg_create function. However, in this process timer->timer_type is not defined to a specific value. Thus, timer->timer_type has garbage value and it occurs kernel panic. So, this commit fixes the panic by initializing timer->timer_type using kzalloc instead of kmalloc.
Test commands: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed
Splat looks like: BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70 Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] dev_attr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? device_remove_bin_file+0x20/0x20 kernfs_seq_show+0xa4/0xb0 seq_read_iter+0x29c/0x750 kernfs_fop_read_iter+0x25a/0x2c0 ? __fsnotify_parent+0x3d1/0x570 ? iov_iter_init+0x70/0x90 new_sync_read+0x2a7/0x3d0 ? __x64_sys_llseek+0x230/0x230 ? rw_verify_area+0x81/0x150 vfs_read+0x17b/0x240 ksys_read+0xd9/0x180 ? vfs_write+0x460/0x460 ? do_syscall_64+0x16/0xc0 ? lockdep_hardirqs_on+0x79/0x120 __x64_sys_read+0x43/0x50 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0cdc819142 Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142 RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003 RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000 R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
{
"affected": [],
"aliases": [
"CVE-2021-47451"
],
"database_specific": {
"cwe_ids": [
"CWE-908"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-22T07:15:10Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value\n\nCurrently, when the rule related to IDLETIMER is added, idletimer_tg timer\nstructure is initialized by kmalloc on executing idletimer_tg_create\nfunction. However, in this process timer-\u003etimer_type is not defined to\na specific value. Thus, timer-\u003etimer_type has garbage value and it occurs\nkernel panic. So, this commit fixes the panic by initializing\ntimer-\u003etimer_type using kzalloc instead of kmalloc.\n\nTest commands:\n # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test\n $ cat /sys/class/xt_idletimer/timers/test\n Killed\n\nSplat looks like:\n BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70\n Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917\n CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014\n Call Trace:\n dump_stack_lvl+0x6e/0x9c\n kasan_report.cold+0x112/0x117\n ? alarm_expires_remaining+0x49/0x70\n __asan_load8+0x86/0xb0\n alarm_expires_remaining+0x49/0x70\n idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d]\n dev_attr_show+0x3c/0x60\n sysfs_kf_seq_show+0x11d/0x1f0\n ? device_remove_bin_file+0x20/0x20\n kernfs_seq_show+0xa4/0xb0\n seq_read_iter+0x29c/0x750\n kernfs_fop_read_iter+0x25a/0x2c0\n ? __fsnotify_parent+0x3d1/0x570\n ? iov_iter_init+0x70/0x90\n new_sync_read+0x2a7/0x3d0\n ? __x64_sys_llseek+0x230/0x230\n ? rw_verify_area+0x81/0x150\n vfs_read+0x17b/0x240\n ksys_read+0xd9/0x180\n ? vfs_write+0x460/0x460\n ? do_syscall_64+0x16/0xc0\n ? lockdep_hardirqs_on+0x79/0x120\n __x64_sys_read+0x43/0x50\n do_syscall_64+0x3b/0xc0\n entry_SYSCALL_64_after_hwframe+0x44/0xae\n RIP: 0033:0x7f0cdc819142\n Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 \u003c48\u003e 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24\n RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000\n RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142\n RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003\n RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000\n R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0\n R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000",
"id": "GHSA-q6h5-3vm3-9h46",
"modified": "2025-09-24T03:30:25Z",
"published": "2024-05-22T09:31:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47451"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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