{"cve":"CVE-2022-49977","nvd":{"published":"2025-06-18T11:15:25.120","modified":"2026-08-04T10:18:01.660","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead\n\nftrace_startup does not remove ops from ftrace_ops_list when\nftrace_startup_enable fails:\n\nregister_ftrace_function\n  ftrace_startup\n    __register_ftrace_function\n      ...\n      add_ftrace_ops(&ftrace_ops_list, ops)\n      ...\n    ...\n    ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1\n    ...\n  return 0 // ops is in the ftrace_ops_list.\n\nWhen ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything:\nunregister_ftrace_function\n  ftrace_shutdown\n    if (unlikely(ftrace_disabled))\n            return -ENODEV;  // return here, __unregister_ftrace_function is not executed,\n                             // as a result, ops is still in the ftrace_ops_list\n    __unregister_ftrace_function\n    ...\n\nIf ops is dynamically allocated, it will be free later, in this case,\nis_ftrace_trampoline accesses NULL pointer:\n\nis_ftrace_trampoline\n  ftrace_ops_trampoline\n    do_for_each_ftrace_op(op, ftrace_ops_list) // OOPS! op may be NULL!\n\nSyzkaller reports as follows:\n[ 1203.506103] BUG: kernel NULL pointer dereference, address: 000000000000010b\n[ 1203.508039] #PF: supervisor read access in kernel mode\n[ 1203.508798] #PF: error_code(0x0000) - not-present page\n[ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0\n[ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI\n[ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Tainted: G    B   W         5.10.0 #8\n[ 1203.512324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014\n[ 1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0\n[ 1203.514644] Code: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00\n[ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246\n[ 1203.520092] RAX: 0000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866\n[ 1203.521469] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000000010b\n[ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07\n[ 1203.523550] R10: fffffbfff1be3160 R11: 0000000000000001 R12: 0000000000478399\n[ 1203.524596] R13: 0000000000000000 R14: ffff888145088000 R15: 0000000000000008\n[ 1203.525634] FS:  00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000\n[ 1203.526801] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 1203.527626] CR2: 000000000000010b CR3: 0000000170e1e001 CR4: 00000000003706e0\n[ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n\nTherefore, when ftrace_startup_enable fails, we need to rollback registration\nprocess and remove ops from ftrace_ops_list.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/4c34a2a6c9927c239dd2e295a03d49b37b618d2c","https://git.kernel.org/stable/c/8569b4ada1e0b9bfaa125bd0c0967918b6560fa2","https://git.kernel.org/stable/c/934e49f7d696afdae9f979abe3f308408184e17b","https://git.kernel.org/stable/c/c3b0f72e805f0801f05fa2aa52011c4bfc694c44","https://git.kernel.org/stable/c/d81bd6671f45fde4c3ac7fd7733c6e3082ae9d8e"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:03:23.287444849+00:00"},"epss":{"cve":"CVE-2022-49977","score":0.00265,"percentile":0.18501,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}