{"id":"CVE-2025-21889","state":"PUBLISHED","title":"perf/core: Add RCU read lock protection to perf_iterate_ctx()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Add RCU read lock protection to perf_iterate_ctx()\n\nThe perf_iterate_ctx() function performs RCU list traversal but\ncurrently lacks RCU read lock protection. This causes lockdep warnings\nwhen running perf probe with unshare(1) under CONFIG_PROVE_RCU_LIST=y:\n\n\tWARNING: suspicious RCU usage\n\tkernel/events/core.c:8168 RCU-list traversed in non-reader section!!\n\n\t Call Trace:\n\t  lockdep_rcu_suspicious\n\t  ? perf_event_addr_filters_apply\n\t  perf_iterate_ctx\n\t  perf_event_exec\n\t  begin_new_exec\n\t  ? load_elf_phdrs\n\t  load_elf_binary\n\t  ? lock_acquire\n\t  ? find_held_lock\n\t  ? bprm_execve\n\t  bprm_execve\n\t  do_execveat_common.isra.0\n\t  __x64_sys_execve\n\t  do_syscall_64\n\t  entry_SYSCALL_64_after_hwframe\n\nThis protection was previously present but was removed in commit\nbd2756811766 (\"perf: Rewrite core context handling\"). Add back the\nnecessary rcu_read_lock()/rcu_read_unlock() pair around\nperf_iterate_ctx() call in perf_event_exec().\n\n[ mingo: Use scoped_guard() as suggested by Peter ]","publishedAt":"2025-03-27T14:57:15.897Z","updatedAt":"2026-10-15T21:51:54.984Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"f390c2eea571945f357a2d3b9fcb1c015767132e","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"a2475ccad6120546ea45dbcd6cd1f74dc565ef6b","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"dd536566dda9a551fc2a2acfab5313a5bb13ed02","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"0fe8813baf4b2e865d3b2c735ce1a15b86002c74","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/events/core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.81","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.18","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.6","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/events/core.c"]}],"references":["https://git.kernel.org/stable/c/f390c2eea571945f357a2d3b9fcb1c015767132e","https://git.kernel.org/stable/c/a2475ccad6120546ea45dbcd6cd1f74dc565ef6b","https://git.kernel.org/stable/c/dd536566dda9a551fc2a2acfab5313a5bb13ed02","https://git.kernel.org/stable/c/0fe8813baf4b2e865d3b2c735ce1a15b86002c74"],"weaknesses":[],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21889.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21889","state":"PUBLISHED","datePublished":"2025-03-27T14:57:15.897Z","dateUpdated":"2026-10-15T21:51:54.984Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.782Z"},"containers":{"cna":{"title":"perf/core: Add RCU read lock protection to perf_iterate_ctx()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Add RCU read lock protection to perf_iterate_ctx()\n\nThe perf_iterate_ctx() function performs RCU list traversal but\ncurrently lacks RCU read lock protection. This causes lockdep warnings\nwhen running perf probe with unshare(1) under CONFIG_PROVE_RCU_LIST=y:\n\n\tWARNING: suspicious RCU usage\n\tkernel/events/core.c:8168 RCU-list traversed in non-reader section!!\n\n\t Call Trace:\n\t  lockdep_rcu_suspicious\n\t  ? perf_event_addr_filters_apply\n\t  perf_iterate_ctx\n\t  perf_event_exec\n\t  begin_new_exec\n\t  ? load_elf_phdrs\n\t  load_elf_binary\n\t  ? lock_acquire\n\t  ? find_held_lock\n\t  ? bprm_execve\n\t  bprm_execve\n\t  do_execveat_common.isra.0\n\t  __x64_sys_execve\n\t  do_syscall_64\n\t  entry_SYSCALL_64_after_hwframe\n\nThis protection was previously present but was removed in commit\nbd2756811766 (\"perf: Rewrite core context handling\"). Add back the\nnecessary rcu_read_lock()/rcu_read_unlock() pair around\nperf_iterate_ctx() call in perf_event_exec().\n\n[ mingo: Use scoped_guard() as suggested by Peter ]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"f390c2eea571945f357a2d3b9fcb1c015767132e","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"a2475ccad6120546ea45dbcd6cd1f74dc565ef6b","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"dd536566dda9a551fc2a2acfab5313a5bb13ed02","versionType":"git"},{"version":"bd27568117664b8b3e259721393df420ed51f57b","status":"affected","lessThan":"0fe8813baf4b2e865d3b2c735ce1a15b86002c74","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/events/core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.81","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.18","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.6","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/events/core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f390c2eea571945f357a2d3b9fcb1c015767132e"},{"url":"https://git.kernel.org/stable/c/a2475ccad6120546ea45dbcd6cd1f74dc565ef6b"},{"url":"https://git.kernel.org/stable/c/dd536566dda9a551fc2a2acfab5313a5bb13ed02"},{"url":"https://git.kernel.org/stable/c/0fe8813baf4b2e865d3b2c735ce1a15b86002c74"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is entered through local syscalls only — `execve()` reaching `perf_event_exec()` via `begin_new_exec()`, with the racing side driven by `perf_event_open()`/`close()`. No network or remote input reaches this code.\nAC:L - The attacker controls both sides of the race, looping `execve()` in one process while closing perf event fds attached to it from another, and can widen the window arbitrarily via CPU pinning and the cross-CPU IPI that `perf_event_stop()` issues inside the unprotected walk. Nothing about the trigger depends on conditions outside the attacker's influence.\nPR:L - An ordinary unprivileged user suffices: `sysctl_perf_event_paranoid` defaults to 2, which permits task-bound user-space perf events on same-uid processes, and no capability is checked anywhere on the `execve()` side of the race.\nUI:N - Both the exec'ing process and the event-closing process are attacker-controlled; no victim action or cooperation is needed.\nS:U - The corruption stays within the kernel's own security authority — a standard local kernel memory-safety flaw with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The unprotected RCU walk dereferences a freed `struct perf_event`, and the reclaimed slot can be groomed with attacker-sprayed perf events, giving a use-after-free read primitive that leaks kernel memory and pointers.\nI:H - `perf_event_addr_filters_exec()` writes into the freed object — zeroing `addr_filter_ranges[count].start/.size` through a pointer read out of reclaimed memory and incrementing `addr_filters_gen` — yielding an attacker-influenced kernel write suitable for privilege escalation.\nA:H - Traversing a freed list entry corrupts the walk and readily produces list corruption, an oops, or a full kernel panic, and the race can be retriggered in a loop."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:55:10.093Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.12.18"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.13.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-21889","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:43:34.538197Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:51:54.984Z"}}]}}}