{"id":"CVE-2023-53668","summary":"ring-buffer: Fix deadloop issue on reading trace_pipe","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix deadloop issue on reading trace_pipe\n\nSoft lockup occurs when reading file 'trace_pipe':\n\n  watchdog: BUG: soft lockup - CPU#6 stuck for 22s! [cat:4488]\n  [...]\n  RIP: 0010:ring_buffer_empty_cpu+0xed/0x170\n  RSP: 0018:ffff88810dd6fc48 EFLAGS: 00000246\n  RAX: 0000000000000000 RBX: 0000000000000246 RCX: ffffffff93d1aaeb\n  RDX: ffff88810a280040 RSI: 0000000000000008 RDI: ffff88811164b218\n  RBP: ffff88811164b218 R08: 0000000000000000 R09: ffff88815156600f\n  R10: ffffed102a2acc01 R11: 0000000000000001 R12: 0000000051651901\n  R13: 0000000000000000 R14: ffff888115e49500 R15: 0000000000000000\n  [...]\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007f8d853c2000 CR3: 000000010dcd8000 CR4: 00000000000006e0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   __find_next_entry+0x1a8/0x4b0\n   ? peek_next_entry+0x250/0x250\n   ? down_write+0xa5/0x120\n   ? down_write_killable+0x130/0x130\n   trace_find_next_entry_inc+0x3b/0x1d0\n   tracing_read_pipe+0x423/0xae0\n   ? tracing_splice_read_pipe+0xcb0/0xcb0\n   vfs_read+0x16b/0x490\n   ksys_read+0x105/0x210\n   ? __ia32_sys_pwrite64+0x200/0x200\n   ? switch_fpu_return+0x108/0x220\n   do_syscall_64+0x33/0x40\n   entry_SYSCALL_64_after_hwframe+0x61/0xc6\n\nThrough the vmcore, I found it's because in tracing_read_pipe(),\nring_buffer_empty_cpu() found some buffer is not empty but then it\ncannot read anything due to \"rb_num_of_entries() == 0\" always true,\nThen it infinitely loop the procedure due to user buffer not been\nfilled, see following code path:\n\n  tracing_read_pipe() {\n    ... ...\n    waitagain:\n      tracing_wait_pipe() // 1. find non-empty buffer here\n      trace_find_next_entry_inc()  // 2. loop here try to find an entry\n        __find_next_entry()\n          ring_buffer_empty_cpu();  // 3. find non-empty buffer\n          peek_next_entry()  // 4. but peek always return NULL\n            ring_buffer_peek()\n              rb_buffer_peek()\n                rb_get_reader_page()\n                  // 5. because rb_num_of_entries() == 0 always true here\n                  //    then return NULL\n      // 6. user buffer not been filled so goto 'waitgain'\n      //    and eventually leads to an deadloop in kernel!!!\n  }\n\nBy some analyzing, I found that when resetting ringbuffer, the 'entries'\nof its pages are not all cleared (see rb_reset_cpu()). Then when reducing\nthe ringbuffer, and if some reduced pages exist dirty 'entries' data, they\nwill be added into 'cpu_buffer-\u003eoverrun' (see rb_remove_pages()), which\ncause wrong 'overrun' count and eventually cause the deadloop issue.\n\nTo fix it, we need to clear every pages in rb_reset_cpu().","modified":"2026-04-02T09:44:48.570835Z","published":"2025-10-07T15:21:26.164Z","related":["SUSE-SU-2025:21040-1","SUSE-SU-2025:21052-1","SUSE-SU-2025:21056-1","SUSE-SU-2025:21064-1","SUSE-SU-2025:4057-1","SUSE-SU-2025:4111-1","SUSE-SU-2025:4128-1","SUSE-SU-2025:4132-1","SUSE-SU-2025:4139-1","SUSE-SU-2025:4140-1","SUSE-SU-2025:4141-1","SUSE-SU-2025:4149-1","SUSE-SU-2025:4189-1","SUSE-SU-2025:4301-1","SUSE-SU-2025:4320-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53668.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0a29dae5786d263016a9aceb1e56bf3fd4cc6fa0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/27bdd93e44cc28dd9b94893fae146b83d4f5b31e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e68f1f3a20fe9b6bde018e353269fbfa289609c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7e42907f3a7b4ce3a2d1757f6d78336984daf8f5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8b0b63fdac6b70a45614e7d4b30e5bbb93deb007"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a55e8a3596048c2f7b574049aeb1885b5abba1cc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb14a93bccc92766b1d9302c6bcbea17d4bce306"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e84829522fc72bb43556b31575731de0440ac0dd"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53668.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53668"},{"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":"a5fb833172eca69136e9ee1ada778e404086ab8a"},{"fixed":"0a29dae5786d263016a9aceb1e56bf3fd4cc6fa0"},{"fixed":"a55e8a3596048c2f7b574049aeb1885b5abba1cc"},{"fixed":"e84829522fc72bb43556b31575731de0440ac0dd"},{"fixed":"5e68f1f3a20fe9b6bde018e353269fbfa289609c"},{"fixed":"bb14a93bccc92766b1d9302c6bcbea17d4bce306"},{"fixed":"8b0b63fdac6b70a45614e7d4b30e5bbb93deb007"},{"fixed":"27bdd93e44cc28dd9b94893fae146b83d4f5b31e"},{"fixed":"7e42907f3a7b4ce3a2d1757f6d78336984daf8f5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53668.json"}}],"schema_version":"1.7.5"}