{"id":"CVE-2026-74387","revision":"052e4522076e4ede8370cd27735c7081","records":[{"revision":"052e4522076e4ede8370cd27735c7081","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74387","aliases":[],"title":"ALSA: seq: midi: Serialize output teardown with event_input","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: midi: Serialize output teardown with event_input\n\nevent_process_midi() borrows msynth->output_rfile.output and then\npasses the substream to dump_midi() and snd_rawmidi_kernel_write()\nwithout synchronizing with the output open/close transition.\nmidisynth_use() also publishes output_rfile before\nsnd_rawmidi_output_params() has finished.\n\nThe last midisynth_unuse() can therefore release the same rawmidi file\nand free substream->runtime before snd_rawmidi_kernel_write1() takes\nits runtime buffer reference. That leaves the event_input path using a\nstale substream or runtime and can end in a NULL-deref or use-after-free.\n\nFix this with two pieces of synchronization. Keep a short IRQ-safe\nspinlock only for publishing or clearing output_rfile and for pairing\nthe output snapshot with an snd_use_lock_t reference. Once\nevent_process_midi() has taken that in-flight reference, it drops the\nspinlock before calling snd_seq_dump_var_event(), dump_midi(), or\nsnd_rawmidi_kernel_write(). midisynth_unuse() now detaches the visible\nrawmidi file under the same spinlock, waits for the in-flight writers\nto drain, and only then drains and releases the saved file.\nmidisynth_use() likewise opens into a local snd_rawmidi_file and\npublishes it only after snd_rawmidi_output_params() succeeds.\n\nThe buggy scenario involves two paths, with each column showing the\norder within that path:\n\nevent_input path: last unuse path:\n1. event_process_midi() snapshots 1. midisynth_unuse() starts\n output_rfile.output. tearing down output_rfile.\n2. dump_midi() reaches 2. snd_rawmidi_kernel_release()\n snd_rawmidi_kernel_write() closes the output file.\n before runtime is pinned. 3. close_substream() frees\n3. The callback keeps using substream->runtime.\n the borrowed substream.\n\nValidation reproduced this kernel report:\nKASAN null-ptr-deref in snd_rawmidi_kernel_write1+0x56/0x360\nRIP: 0033:0x7fde7dd0837f\nRIP: 0010:snd_rawmidi_kernel_write1+0x56/0x360","state":0,"publishedAt":"2026-08-15T05:59:02.457+00:00","modifiedAt":"2026-10-16T18:55:36.992+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"sound/core/seq/seq_midi.c\"\n ],\n \"versions\": [\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"f5d470b808bc01f70978e22e595c6f7768313406\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"936641af564c3d92721704b781e36aaf223efdd2\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"718f6a56b40875f19e6915799044a02df9abfd52\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"11165fe2c5ea0516debe486d91df67abbe36905e\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"d6fd2afb137f52bf00c5210cc44d08ed54dcffb4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\n \"lessThan\": \"ef7607ab1c8adc6258fb1b27d08e26aecdc18a58\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"sound/core/seq/seq_midi.c\"\n ],\n \"versions\": [\n {\n \"version\": \"2.6.12\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"2.6.12\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.178\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.145\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.97\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.40\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.5\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/f5d470b808bc01f70978e22e595c6f7768313406","https://git.kernel.org/stable/c/936641af564c3d92721704b781e36aaf223efdd2","https://git.kernel.org/stable/c/718f6a56b40875f19e6915799044a02df9abfd52","https://git.kernel.org/stable/c/11165fe2c5ea0516debe486d91df67abbe36905e","https://git.kernel.org/stable/c/d6fd2afb137f52bf00c5210cc44d08ed54dcffb4","https://git.kernel.org/stable/c/ef7607ab1c8adc6258fb1b27d08e26aecdc18a58"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74387","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74387","identifiers":["CVE-2026-74387"]},"retained":false,"historicalAffected":[]}],"coverage":[]}