In the Linux kernel, the following vulnerability has been resolved: ALSA: ump: do not touch legacy_rmidi before it exists snd_ump_parse_endpoint() sets ump->parsed on every exit, including error, before the caller attaches the legacy rawmidi device. ump_handle_ep_name_msg() then treats parsed as "legacy_rmidi is live" and calls ump_legacy_set_rawmidi_name(), which snprintf()s into ump->legacy_rmidi->name. If a UMP packet arrives in that window (IRQ path from snd_ump_receive), legacy_rmidi is still NULL (KASAN null-ptr-deref in snprintf). Guard the legacy helpers. parsed only means endpoint info was parsed, not that legacy_rmidi exists.
https://git.kernel.org/stable/c/adeee7187694719890aaffdc14b7e89cfd736f1d
https://git.kernel.org/stable/c/a4cef20cd473e0640fefd38094d4baac0ec76ae3
https://git.kernel.org/stable/c/228075f31b141395233218712242913125ace4e0
https://git.kernel.org/stable/c/1c8e01792adf91879322f1ad752f1814de8b7e7d