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=1794049753; b=IzhY7KLRA7+XP9HNy8uneidxGOoj6RGpuo3+DBN5drZWlKpAZWwUGzk3PaVNMzzFQR39 IuJ14xs7H+15QWW21Ab6f+tIt/sbxrFzN1gPhKK+b0l19sDf/YDFJ2npGfDnsxMdOjxde 1qZtbq/YHzv+9mX9nDNy61IKwIcZ/O8cx15YCbi963MC53iJgJnX4tJWRnwhflsvGFwhv Gcx0LUdOSiubHwht8FOMHwyBJSsQhZ2j0SpQPHXdmAtGCqPi2bdVnQK3Th6yKPOCOhuag qC38Fd/IYFMnwVO9ULyAtIY8I8DY56qfF8LfG9takv3DjFfm86FWlsCpNAM45I+vCUw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049753; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=zoY0mW0yWh5MAAG7NmUtpC7RYqrNTKF/NHFZQY2ngMg=; b=RP0D1eDDrwqrypILPg19tuCXzTB6yEev3yTCNnIftaG8YzlOP/GDMNxfSS/JNCpdBFj+ 46kyNkY4Ep0f+CnNSegf0LId+Dyt1fl/PZY6fgLYkjcsADK8N2+qVcm9SemARICWa1FOg cwFiqaUD609aRtCGHa7DxScldt4b12a+KqV+e+bWgUXx7RXo9Ft2fsQszKFLfS/b0TLA4 yxj3gdr8JmHfmjctgVVWkuM+7vKqxUtOpfsJukbzgbVGS/lVaJ5W9PVfBwbuPv3fGByd6 pe4tsyTBwZAeRLp7/m/dsLUTYKddNShQiNEhcdm2zMHSenEqVfTWI6fogQo8Fy0UJ5g== 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=UbjfLtB8; 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 B2714606A326 for ; Sat, 7 Nov 2026 11:09:12 +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=UbjfLtB8 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C89C1F008A1; Sat, 7 Nov 2026 11:09:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049752; bh=zoY0mW0yWh5MAAG7NmUtpC7RYqrNTKF/NHFZQY2ngMg=; h=From:To:Cc:Subject:Date; b=UbjfLtB8OpwrIFq2Rs2DWzr+ZzKxBLpQDeLRY76FF8dXYKs07q3j04ufOYe1Oyz5Y kV8RTcyndLzM23yiMRBW6JcsMo7SGToCSjX5AqW6sF8OZ4IgEp8dExctwBveVjLhdL 8vEJ319hZeH6NKCC6yfCWup4UptaJy3eiwh2zIALNeM99CFOExesliuVIf0cEdrGkL +eSEsoSB5KeFzIjGfhrm0lbhWchIq2t34eWofdyfyMTY116txduIS4nAMaxgNaK/Jy 58oiu9MBIffU/3D1HpT36+15PIwi+ZomwyF0NIS+DoycxFTsWagJmHJvoKMdLJP07N vSxGM83/JYcLA== 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 5.15-stable tree Date: Sat, 7 Nov 2026 06:09:10 -0500 Message-ID: <20261107060910-failed-5.15-34e3e04b8a17@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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 34e3e04b8a1731a773797542f0781e99ce7cd755 # git commit -s git send-email --to '' --in-reply-to '20261107060910-failed-5.15-34e3e04b8a17@kernel.org' --subject-prefix 'PATCH 5.15.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