In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: seq: midi: Serialize input teardown with event_input<\/p>\n
snd_midi_input_event() must not be running while a rawmidi substream is
\nclosing, since this can lead to the trigger state becoming out-of-step
\nthrough this sequence in snd_rawmidi_input_trigger():<\/p>\n
\tsnd_rawmidi_input_trigger(up=0)
\n\t\t\t\t\tsnd_midi_input_event()
\n\t\t\t\t\t -> snd_rawmidi_kernel_read()
\n\t\t\t\t\t -> snd_rawmidi_input_trigger(up=1)
\n\t -> cancel_work_sync()<\/p>\n
which ends with the underlying device being active unexpectedly.<\/p>\n
When this is called from close_substream(), further input can re-trigger
\nthe input event leaving it running after rawmidi_release_priv() has set
\nrfile->rmidi to NULL which leads to:<\/p>\n
\tUnable to handle kernel NULL pointer dereference at virtual address 00000000000000b0
\n\tCall trace:
\n\t snd_midi_input_event+0x3c\/0x134 [snd_seq_midi] (P)
\n\t snd_rawmidi_input_event_work+0x1c\/0x2c
\n\t process_one_work+0x150\/0x3a4
\n\t worker_thread+0x190\/0x318<\/p>\n
Apply a similar approach to commit ef7607ab1c8ad (“ALSA: seq: midi:
\nSerialize output teardown with event_input”) which fixed the same issue
\nin the output direction, but updated to use RCU following Takashi Iwai’s
\nproposed follow-on patch [1].<\/p>\n
With this change in place, midisynth_unsubscribe() clears the input file
\nso snd_midi_input_event() will not re-trigger the stream and will be
\nquiesced by the cancel_work_sync() in snd_rawmidi_input_trigger().<\/p>\n
[1] https:\/\/lore.kernel.org\/linux-sound\/20260813144224.753399-1-tiwai@suse.de\/<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: seq: midi: Serialize input teardown with event_input<\/p>\n
snd_midi_input_event() must not be running while a rawmidi substream is<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25616","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25616","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}