{"id":"CVE-2026-74601","summary":"ring-buffer: Use current_context for safe per-CPU buffer swap","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Use current_context for safe per-CPU buffer swap\n\nThe ring_buffer_swap_cpu() function currently checks the per-CPU\ncommitting counter to determine if a buffer is actively being written to\nbefore performing the swap. However, there exists a race window where\nthis check can be bypassed:\n\n    ring_buffer_lock_reserve\n        cpu_buffer = buffer-\u003ebuffers[cpu];       // cpu_buffer_a\n        rb_reserve_next_event\n            rb_start_commit // inc committing\n            if (unlikely(READ_ONCE(cpu_buffer-\u003ebuffer) != buffer)) {...}\n            __rb_reserve_next\n                rb_move_tail\n                    rb_end_commit(cpu_buffer);   // dec committing =\u003e 0\n                    /* interrupt hits here, successfully swaps! */\n                    local_inc(&cpu_buffer-\u003ecommitting);\n\n    ring_buffer_unlock_commit\n        cpu_buffer = buffer-\u003ebuffers[cpu];      // cpu_buffer_b\n        rb_commit\n            rb_end_commit\n            RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer-\u003ecommitting))\n                                                // triggers warning\n\nThe committing counter can temporarily drop to 0 during a single write\noperation (within rb_move_tail), creating a window where swap can\nsucceed even though the write is still in progress. This leads to\ninconsistent buffer state and triggers the RB_WARN_ON in rb_commit().\n\nReplace the committing counter check with current_context checks, which\nare set at the entry of ring_buffer_lock_reserve() and remain valid\nthroughout the entire write operation, providing a reliable indicator of\nbuffer busy state during swap.","modified":"2026-08-24T11:47:07.605845594Z","published":"2026-08-22T15:31:50.092Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74601.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/22709117d9ae95e52673685f98caac7c356a8227"},{"type":"WEB","url":"https://git.kernel.org/stable/c/26662bc8fced1d668fa1aa146eda085bfc67bd0b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/597f279b7b4a06412e3d965e98cc36e181cdbede"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5b926fb04cb9ef3156dcf88c69a59d3d1a1c4f9f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e6e2a18c20e88167d414f666032792e8bf19b80"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6b524e6b234e45c7f5f90d13b042c6f57f80105c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ad7e10c7ea89af45ac1bf1814855d45da472703d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f27bdc43077e4fcb5557dfc315ee8d91e741f483"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74601.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74601"},{"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":"4239c38fe0b3847e1e6d962c74b41b08ba0e2990"},{"fixed":"26662bc8fced1d668fa1aa146eda085bfc67bd0b"},{"fixed":"6b524e6b234e45c7f5f90d13b042c6f57f80105c"},{"fixed":"597f279b7b4a06412e3d965e98cc36e181cdbede"},{"fixed":"22709117d9ae95e52673685f98caac7c356a8227"},{"fixed":"ad7e10c7ea89af45ac1bf1814855d45da472703d"},{"fixed":"5b926fb04cb9ef3156dcf88c69a59d3d1a1c4f9f"},{"fixed":"5e6e2a18c20e88167d414f666032792e8bf19b80"},{"fixed":"f27bdc43077e4fcb5557dfc315ee8d91e741f483"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74601.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.5.0"},{"fixed":"5.10.266"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.217"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.184"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.153"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.105"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74601.json"}}],"schema_version":"1.9.0"}