{"id":"DEBIAN-CVE-2022-49781","details":"In the Linux kernel, the following vulnerability has been resolved:  perf/x86/amd: Fix crash due to race between amd_pmu_enable_all, perf NMI and throttling  amd_pmu_enable_all() does:        if (!test_bit(idx, cpuc-\u003eactive_mask))               continue;        amd_pmu_enable_event(cpuc-\u003eevents[idx]);  A perf NMI of another event can come between these two steps. Perf NMI handler internally disables and enables _all_ events, including the one which nmi-intercepted amd_pmu_enable_all() was in process of enabling. If that unintentionally enabled event has very low sampling period and causes immediate successive NMI, causing the event to be throttled, cpuc-\u003eevents[idx] and cpuc-\u003eactive_mask gets cleared by x86_pmu_stop(). This will result in amd_pmu_enable_event() getting called with event=NULL when amd_pmu_enable_all() resumes after handling the NMIs. This causes a kernel crash:    BUG: kernel NULL pointer dereference, address: 0000000000000198   #PF: supervisor read access in kernel mode   #PF: error_code(0x0000) - not-present page   [...]   Call Trace:    \u003cTASK\u003e    amd_pmu_enable_all+0x68/0xb0    ctx_resched+0xd9/0x150    event_function+0xb8/0x130    ? hrtimer_start_range_ns+0x141/0x4a0    ? perf_duration_warn+0x30/0x30    remote_function+0x4d/0x60    __flush_smp_call_function_queue+0xc4/0x500    flush_smp_call_function_queue+0x11d/0x1b0    do_idle+0x18f/0x2d0    cpu_startup_entry+0x19/0x20    start_secondary+0x121/0x160    secondary_startup_64_no_verify+0xe5/0xeb    \u003c/TASK\u003e  amd_pmu_disable_all()/amd_pmu_enable_all() calls inside perf NMI handler were recently added as part of BRS enablement but I'm not sure whether we really need them. We can just disable BRS in the beginning and enable it back while returning from NMI. This will solve the issue by not enabling those events whose active_masks are set but are not yet enabled in hw pmu.","modified":"2026-08-27T23:04:30.538521616Z","published":"2025-05-01T15:16:01.307Z","upstream":["CVE-2022-49781"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2022-49781"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49781.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49781.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49781.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}