From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047839; b=iNc58i0tMrY+hMjiKGCvftc8SsBMQ9J4zW/5uE1Vc0UbEI0Nhgg7/H9gL7pkbRexKG/4 6IEf1eWOqS0lsEEd1Gf2EHPi/5qYKhguEikahZjGKd2tH0pULXPv0FpgQnrp32ZhxL1M1 FoJ6BSS/Nrl4th0NOyAAc4UhByhIMcCwCXOu/M/WaOd1VR9KYNfMpY4OBKnLNujwVVA5X cK7XyXdtg+SAfr5/sNsTWzao+te8lajhPBcO9PJxi5rH3xWiy6VJ6Swtr/qlL1+SHAvWM O/OLuDFMuOJX80bHPJIektplpyiD6ByOBcEtw4E0znBVuEKKVLNVehjAqxBfSTr0qAw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047839; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=5ZL/a9/oMEC6zxOdqYi6O+megj0G3z8O2shAO37ToUc=; b=vlGvwRASHYRLE4ADNt16jmvA4abbZeVBcFCXL7KlmII0/roNgnS/MbSnCA6xGsa8ErCY ZNlYJvcplikdZ/Fe5YuICy1CWfnJf+ljA6j3upn1RsmhsmU+PBdujLlJpGU8Q9urV+n/5 iZydN+6zWnhx6uENFTLLHlp3aEcxyNRSExaIeozmKP9BxVBEVVW+WDK0jfqBRklh6gRfk uimIukxCudAXyLy0B0E6SvPGXSFv+8/qgILQdYjtogEkDtDhc7YgcVBmdpdCIV9E4CwSP VpBPXS70JcE2mc/RPDM6mGx4yeNtBjR3bCmFzDP4SgkfpUNkAdCw3WjRiljqa2s8NwA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lfxMStAh; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 709ED606A332 for ; Sat, 7 Nov 2026 10:37:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lfxMStAh Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1BDF1F0089F; Sat, 7 Nov 2026 10:37:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047839; bh=5ZL/a9/oMEC6zxOdqYi6O+megj0G3z8O2shAO37ToUc=; h=From:To:Cc:Subject:Date; b=lfxMStAh3QSi5UZsWoQQ6A+MvDVpFH1FTj14JxVOh6qV6EalHetcxCZ/UQwTQCPCD KhIgcXT46hu+xW1g4uJDlPOH2Nb3e968gCbJNMwAuHl227SFVWKC7wvGGZqHYyfS3s GEuH7crk8jm8BGX8TjWDETm3TMck2Qq9YewDt+RRhceRPm8JmImTWEncMxQrPO57oK rwlvUhIEC4yL7sQeBgOWn2AnwOh9fQ+8B/F9JVStj0CHCPnSF+yiwJ32fP1a/uCOSp iftdpYnyAmzyTZ9k+2nhor3wSqVbCH91T1GRPVY0krmWJKI/KVoD2QPTNzSzfynU47 l2kzqZnGNubfA== From: Sasha Levin To: tiwai@suse.de, sashiko-bot@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] ALSA: emux: Fix UAF of soundfont zones at note-on" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:37:17 -0500 Message-ID: <20261107053717-failed-6.6-34e3e04b8a17@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 34e3e04b8a1731a773797542f0781e99ce7cd755 # git commit -s git send-email --to '' --in-reply-to '20261107053717-failed-6.6-34e3e04b8a17@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 34e3e04b8a1731a773797542f0781e99ce7cd755 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Tue, 20 Oct 2026 12:16:20 +0200 Subject: [PATCH] ALSA: emux: Fix UAF of soundfont zones at note-on snd_emux_note_on() looks up the matching zones via snd_soundfont_search_zone(), which takes sflist->lock only during the lookup and returns the raw zone pointers after releasing it. The caller then stores them in vp->zone without any protection. Meanwhile, a concurrent SNDRV_EMUX_IOCTL_REMOVE_LAST_SAMPLES ioctl may unlink and free those zones in snd_soundfont_remove_unlocked(); this leads to a use-after-free in snd_emux_note_on(), and later at accessing the cached vp->zone, e.g. in snd_emux_send_effect(). Fix it by holding sflist->lock in snd_emux_note_on() over the whole zone lookup and voice setup, and let snd_soundfont_search_zone() require the caller to hold the lock, instead. snd_soundfont_lock_preset() takes sflist->lock for setting presets_locked, so the removal path now syncs with the note-on finish. Reported-by: Sashiko Closes: https://sashiko.dev/#/bug/linux-697212bb-a434-4ff5-8778-25a84f5dad89 Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261020101624.205638-1-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/synth/emux/emux_synth.c | 3 +++ sound/synth/emux/soundfont.c | 9 ++++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/sound/synth/emux/emux_synth.c b/sound/synth/emux/emux_synth.c index 6982e1317da5e..2cbf12364a1e5 100644 --- a/sound/synth/emux/emux_synth.c +++ b/sound/synth/emux/emux_synth.c @@ -60,6 +60,9 @@ snd_emux_note_on(void *p, int note, int vel, struct snd_midi_channel *chan) return; key = note; /* remember the original note */ + + /* hold sflist->lock for protecting against concurrent free */ + guard(spinlock_irqsave)(&emu->sflist->lock); nvoices = get_zone(emu, port, ¬e, vel, chan, table); if (! nvoices) return; diff --git a/sound/synth/emux/soundfont.c b/sound/synth/emux/soundfont.c index c172b53b17a4f..039357d96e07a 100644 --- a/sound/synth/emux/soundfont.c +++ b/sound/synth/emux/soundfont.c @@ -1225,6 +1225,9 @@ delete_preset(struct snd_sf_list *sflist, struct snd_sf_zone *zp) * The found zones are stored on 'table' array. max_layers defines * the maximum number of elements in this array. * This function returns the number of found zones. 0 if not found. + * + * The caller must hold sflist->lock, and keep holding it as long as + * the returned zones are accessed. */ int snd_soundfont_search_zone(struct snd_sf_list *sflist, int *notep, int vel, @@ -1234,11 +1237,11 @@ snd_soundfont_search_zone(struct snd_sf_list *sflist, int *notep, int vel, { int nvoices; - /* this function is supposed to be called atomically, - * so we check the lock. if it's busy, just returns 0 to + lockdep_assert_held(&sflist->lock); + + /* if the presets are being modified, just returns 0 to * tell the caller the busy state */ - guard(spinlock_irqsave)(&sflist->lock); if (sflist->presets_locked) return 0; nvoices = search_zones(sflist, notep, vel, preset, bank, -- 2.53.0