{"id":"CVE-2026-89902","summary":"LoongArch: Avoid preempt count underflow without probe","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Avoid preempt count underflow without probe\n\nLoongArch uses break 11 for the breakpoint placed after an instruction\nthat Kprobes executes out of line. Since userspace can issue the same\nbreak instruction, do_bp() can reach kprobe_singlestep_handler() when\nthere is no current probe.\n\nThe handler actually returns false in this case, but it first calls\npreempt_enable_no_resched(). The corresponding preempt_disable() is done\nby kprobe_breakpoint_handler() on a real Kprobe hit, so it has not run\nhere. As a result, an ordinary userspace breakpoint (code 11) underflows\nthe current task's preempt count.\n\nThis also makes in_interrupt() return true until the task schedules. One\nvisible consequence is the socket cgroup attribution: cgroup_sk_alloc()\ntreats the allocation as interrupt context and assigns the socket to the\nroot cgroup. A socket opened from the SIGTRAP handler can then avoid a\nBPF_CGROUP_INET_SOCK_CREATE policy attached to the task's own cgroup.\n\nReturn as soon as kprobe_running() reports no active probe.\n\nThe same check has appeared in [PATCH v10 2/4] of the original LoongArch\nKprobes series, but was dropped before the feature reached mainline.","modified":"2026-09-18T03:48:33.819747952Z","published":"2026-09-16T10:32:01.655Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89902.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/72ce4b24676e8b3b75376c4c559dd81c1ac52d5a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/76395109a051b53860faaec96522ef08ae9e8e27"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a1cb727fa27c2d9c7859729cd90db7bc0f46957f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c4357ebeee63cb8da1446fc936573a34e68b0f71"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff40e597d5d98c0c45a4d09df8177202fac9520e"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89902.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89902"},{"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":"6d4cc40fb5f58147defc6c0e9d86e6232fe31616"},{"fixed":"ff40e597d5d98c0c45a4d09df8177202fac9520e"},{"fixed":"a1cb727fa27c2d9c7859729cd90db7bc0f46957f"},{"fixed":"76395109a051b53860faaec96522ef08ae9e8e27"},{"fixed":"c4357ebeee63cb8da1446fc936573a34e68b0f71"},{"fixed":"72ce4b24676e8b3b75376c4c559dd81c1ac52d5a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89902.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.3.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89902.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}