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=1794048724; b=pF2OvbZ9pxVocG0NYpwO9gfQz34QpQGJst0N0jXK7ZlTl4iWH0sy05XWFqe8UfDXk0Es OANx5ycupYxQQ/r2Zjgd1SSTAvojV9hbwb1uX6k24lPFYYJFEOKctA2tMq3h8h0mKSV2l Eu3UPiouh7y3Ucp0GXZzUMeFJ9b8g/bQnguGkTFrXMT6UgdBbTkcbLoGYDMcYUYSJbmuY k1gcizvjq/jcjlQo5w1YRaU6U42GVJlRKWYBVoubxanIiM3CQyiSdkL894LByrVBJM2+l tRnT9KMdMBC/RrBdy8yScp9uVjQOCyHCIgUAL2fNaoy4q7KgCJVlvGOS84trI6dsTvw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794048724; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=E39Vf130TZzt3dW6V1ZGChk+p7qcvj1iZKCiXx0CPKs=; b=SRRux9UOyaj/TVxElWIcvujMxwd0Y2PWZhqTpdQtCj0D/eSBKIMxCt/EkAFfRfVo67UU 01u8XKysJENJgOtm44tBDPVPPleTd2Eff1UyrHEHm1eKT4r/SUwM5xm0s3yz3ySjneE6n VkS19XDEnW0QcnbrOXDsLWCxK4H9OWej2k9+VPdzvQck7KXZBHv/z0A1EAGozx6eJM7Hu 4VU/d2Tv4peJaCLg8+7bkTZRlkdyHYtJjIUXpDYpAUZbIvMeoTrOGXnTtd4f3CznaT6gA odTGKHj1IdENcY70nZnvllKIQdJKOCnHUnaMGevFDgFVbuVT+7B7fTC4mLmcMHyTDEA== 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=BRn+4KYE; 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 3499B606A32E for ; Sat, 7 Nov 2026 10:52:04 +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=BRn+4KYE Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76B771F0089F; Sat, 7 Nov 2026 10:52:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794048723; bh=E39Vf130TZzt3dW6V1ZGChk+p7qcvj1iZKCiXx0CPKs=; h=From:To:Cc:Subject:Date; b=BRn+4KYEhwrxRXRaIbMIkDFjawbPwwQ1t5kPVJmxHv5T+nGBydK7OgQJAygFDiG8s QxUTz9QUeBgQfk/xgaQfQMyQ10HrR/ZrNpC4UTy3QR2wZaAWPz6e4waJMGZ6Y8YEuP YT3q52qVXlN8de44YgR1g2LGBoA43laeiSeEHzNqLCQK7BwK33/E+RXIEewxNQkP3p a2faL9OEInxGzxhjSpDH5yaCtWuovbYKLN6Kw/ynWDAErRN50DGp3w7TO8ka6WcA5+ vdc8aBnlOyLeDvAFiwV76N0qKlbeoGC4wIHd9Ppv95zlR3BIi1Z1HA6v0/ILFsmqkF lFS/OXSlVdHOg== 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 6.1-stable tree Date: Sat, 7 Nov 2026 05:52:02 -0500 Message-ID: <20261107055202-failed-6.1-34e3e04b8a17@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 6.1-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-6.1.y git checkout FETCH_HEAD git cherry-pick -x 34e3e04b8a1731a773797542f0781e99ce7cd755 # git commit -s git send-email --to '' --in-reply-to '20261107055202-failed-6.1-34e3e04b8a17@kernel.org' --subject-prefix 'PATCH 6.1.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