{"id":"AZL-64031","summary":"CVE-2025-38063 affecting package kernel for versions less than 6.6.96.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm: fix unconditional IO throttle caused by REQ_PREFLUSH\n\nWhen a bio with REQ_PREFLUSH is submitted to dm, __send_empty_flush()\ngenerates a flush_bio with REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC,\nwhich causes the flush_bio to be throttled by wbt_wait().\n\nAn example from v5.4, similar problem also exists in upstream:\n\n    crash\u003e bt 2091206\n    PID: 2091206  TASK: ffff2050df92a300  CPU: 109  COMMAND: \"kworker/u260:0\"\n     #0 [ffff800084a2f7f0] __switch_to at ffff80004008aeb8\n     #1 [ffff800084a2f820] __schedule at ffff800040bfa0c4\n     #2 [ffff800084a2f880] schedule at ffff800040bfa4b4\n     #3 [ffff800084a2f8a0] io_schedule at ffff800040bfa9c4\n     #4 [ffff800084a2f8c0] rq_qos_wait at ffff8000405925bc\n     #5 [ffff800084a2f940] wbt_wait at ffff8000405bb3a0\n     #6 [ffff800084a2f9a0] __rq_qos_throttle at ffff800040592254\n     #7 [ffff800084a2f9c0] blk_mq_make_request at ffff80004057cf38\n     #8 [ffff800084a2fa60] generic_make_request at ffff800040570138\n     #9 [ffff800084a2fae0] submit_bio at ffff8000405703b4\n    #10 [ffff800084a2fb50] xlog_write_iclog at ffff800001280834 [xfs]\n    #11 [ffff800084a2fbb0] xlog_sync at ffff800001280c3c [xfs]\n    #12 [ffff800084a2fbf0] xlog_state_release_iclog at ffff800001280df4 [xfs]\n    #13 [ffff800084a2fc10] xlog_write at ffff80000128203c [xfs]\n    #14 [ffff800084a2fcd0] xlog_cil_push at ffff8000012846dc [xfs]\n    #15 [ffff800084a2fda0] xlog_cil_push_work at ffff800001284a2c [xfs]\n    #16 [ffff800084a2fdb0] process_one_work at ffff800040111d08\n    #17 [ffff800084a2fe00] worker_thread at ffff8000401121cc\n    #18 [ffff800084a2fe70] kthread at ffff800040118de4\n\nAfter commit 2def2845cc33 (\"xfs: don't allow log IO to be throttled\"),\nthe metadata submitted by xlog_write_iclog() should not be throttled.\nBut due to the existence of the dm layer, throttling flush_bio indirectly\ncauses the metadata bio to be throttled.\n\nFix this by conditionally adding REQ_IDLE to flush_bio.bi_opf, which makes\nwbt_should_throttle() return false to avoid wbt_wait().","modified":"2026-04-01T05:20:15.180103Z","published":"2025-06-18T10:15:39Z","upstream":["CVE-2025-38063"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38063"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.96.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-64031.json"}}],"schema_version":"1.7.5"}