CVE-2026-74502: ALSA: ump: fix double free of out_cvts on rawmidi error

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ALSA: ump: fix double free of out_cvts on rawmidi error

snd_ump_attach_legacy_rawmidi() allocates the legacy conversion array
ump->out_cvts and, on the snd_rawmidi_new() error path, frees it with
kfree() but leaves ump->out_cvts pointing at the freed memory.  When the
endpoint is later torn down, snd_ump_endpoint_free() frees ump->out_cvts
a second time, resulting in a double free.

The host snd-usb-audio driver attaches the legacy rawmidi for any USB
MIDI 2.0 (UMP) device, so a device that makes snd_rawmidi_new() fail
reaches this path on enumeration.

Clear ump->out_cvts after freeing it on the error path so it is not
freed again during teardown.

Discovered by XBOW, triaged by Baul Lee <[email protected]>

The Linux kernel CVE team has assigned CVE-2026-74502 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.5 with commit 33cd7630782df2230529c3e8f1a6d0ae9cd6ab49 and fixed in 6.6.151 with commit e84d2e53a05c78a04d1343eeb0f31a79456e79fc
	Issue introduced in 6.5 with commit 33cd7630782df2230529c3e8f1a6d0ae9cd6ab49 and fixed in 6.12.103 with commit 3302aaeac4f7ee6b775850db21d5f61064ce70ad
	Issue introduced in 6.5 with commit 33cd7630782df2230529c3e8f1a6d0ae9cd6ab49 and fixed in 6.18.44 with commit 032746c2dd9a4ea0774b04ac8a29e2ea628f106e
	Issue introduced in 6.5 with commit 33cd7630782df2230529c3e8f1a6d0ae9cd6ab49 and fixed in 7.1.8 with commit c57001f55f97ef856fb6527e376c5c4a056a53a4
	Issue introduced in 6.5 with commit 33cd7630782df2230529c3e8f1a6d0ae9cd6ab49 and fixed in 7.2-rc6 with commit 70c977815af0d997feb2d0c5d284d55689bf7051

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74502
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	sound/core/ump.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e84d2e53a05c78a04d1343eeb0f31a79456e79fc
	https://git.kernel.org/stable/c/3302aaeac4f7ee6b775850db21d5f61064ce70ad
	https://git.kernel.org/stable/c/032746c2dd9a4ea0774b04ac8a29e2ea628f106e
	https://git.kernel.org/stable/c/c57001f55f97ef856fb6527e376c5c4a056a53a4
	https://git.kernel.org/stable/c/70c977815af0d997feb2d0c5d284d55689bf7051