{"id":"CVE-2025-39813","title":"ftrace: Fix potential warning in trace_printk_seq during ftrace_dump","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nftrace: Fix potential warning in trace_printk_seq during ftrace_dump\n\nWhen calling ftrace_dump_one() concurrently with reading trace_pipe,\na WARN_ON_ONCE() in trace_pri…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < f299353e7ccbcc5c2ed8993c48fbe7609cbe729a","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 5ab0ec206deb99eb3baf8f1d7602aeaa91dbcc85","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < a6f0f8873cc30fd4543b09adf03f7f51d293f0e6","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < e80ff23ba8bdb0f41a1afe2657078e4097d13a9a","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 28c8fb7ae2ad27d81c8de3c4fe608c509f6a18aa","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < ced94e137e6cd5e79c65564841d3b7695d0f5fa3","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < fbd4cf7ee4db65ef36796769fe978e9eba6f0de4","Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 4013aef2ced9b756a410f50d12df9ebe6a883e4a","Linux 2.6.28"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T21:12:05.539187Z"},"published":"2025-09-16","updated":"2026-11-05","sourceUpdated":"2026-11-05T21:12:59.108Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-39813","references":[{"url":"https://git.kernel.org/stable/c/f299353e7ccbcc5c2ed8993c48fbe7609cbe729a"},{"url":"https://git.kernel.org/stable/c/5ab0ec206deb99eb3baf8f1d7602aeaa91dbcc85"},{"url":"https://git.kernel.org/stable/c/a6f0f8873cc30fd4543b09adf03f7f51d293f0e6"},{"url":"https://git.kernel.org/stable/c/e80ff23ba8bdb0f41a1afe2657078e4097d13a9a"},{"url":"https://git.kernel.org/stable/c/28c8fb7ae2ad27d81c8de3c4fe608c509f6a18aa"},{"url":"https://git.kernel.org/stable/c/ced94e137e6cd5e79c65564841d3b7695d0f5fa3"},{"url":"https://git.kernel.org/stable/c/fbd4cf7ee4db65ef36796769fe978e9eba6f0de4"},{"url":"https://git.kernel.org/stable/c/4013aef2ced9b756a410f50d12df9ebe6a883e4a"}],"tags":["cve.org"],"epss":0.00121,"epssPercentile":0.01928,"ingestedAt":"2026-11-05T22:38:32.030Z","slug":"CVE-2025-39813","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nftrace: Fix potential warning in trace_printk_seq during ftrace_dump\n\nWhen calling ftrace_dump_one() concurrently with reading trace_pipe,\na WARN_ON_ONCE() in trace_printk_seq() can be triggered due to a race\ncondition.\n\nThe issue occurs because:\n\nCPU0 (ftrace_dump)                              CPU1 (reader)\necho z > /proc/sysrq-trigger\n\n!trace_empty(&iter)\ntrace_iterator_reset(&iter) <- len = size = 0\n                                                cat /sys/kernel/tracing/trace_pipe\ntrace_find_next_entry_inc(&iter)\n  __find_next_entry\n    ring_buffer_empty_cpu <- all empty\n  return NULL\n\ntrace_printk_seq(&iter.seq)\n  WARN_ON_ONCE(s->seq.len >= s->seq.size)\n\nIn the context between trace_empty() and trace_find_next_entry_inc()\nduring ftrace_dump, the ring buffer data was consumed by other readers.\nThis caused trace_find_next_entry_inc to return NULL, failing to populate\n`iter.seq`. At this point, due to the prior trace_iterator_reset, both\n`iter.seq.len` and `iter.seq.size` were set to 0. Since they are equal,\nthe WARN_ON_ONCE condition is triggered.\n\nMove the trace_printk_seq() into the if block that checks to make sure the\nreturn value of trace_find_next_entry_inc() is non-NULL in\nftrace_dump_one(), ensuring the 'iter.seq' is properly populated before\nsubsequent operations.\n\n## Affected\n\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < f299353e7ccbcc5c2ed8993c48fbe7609cbe729a`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 5ab0ec206deb99eb3baf8f1d7602aeaa91dbcc85`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < a6f0f8873cc30fd4543b09adf03f7f51d293f0e6`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < e80ff23ba8bdb0f41a1afe2657078e4097d13a9a`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 28c8fb7ae2ad27d81c8de3c4fe608c509f6a18aa`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < ced94e137e6cd5e79c65564841d3b7695d0f5fa3`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < fbd4cf7ee4db65ef36796769fe978e9eba6f0de4`\n- `Linux >= d769041f865330034131525ee6a7f72eb4af2a24 < 4013aef2ced9b756a410f50d12df9ebe6a883e4a`\n- `Linux 2.6.28`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}