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=1794591525; b=2AC2oV2faMmEApVO0k9Xplly3aEgJUf4T+n1WepHsju7FZ5XZdlbhnc3s8UMfZXUYZLT LulHxi/BS/3sfgGBhgINYG8k5GfHvnEunzTRmMiGm+/4zliRdrkOUNdNCCzqyC2g2X5gH R3Eh6ZYkkPmF3bt1GU9M8UyZkDATrFMAjR7Ht1Mf9C3vS9NsbikramzWyTUyPjAMhUtQY 6DC7R5KVgrKhYm0GLAJGJv2mmnsA5zZ9Dw46mwhgJOZDuu1S8aBAx4Spdr4dvCSr/KtbP vddGBInKie1f4JXwCsfNGkAVkPPnb+nwRQhqriRFzYSlo0bOeu/WgQn8iZ3G7nQv7Jg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794591525; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=RoUA1KIcSQAwTa7CT6jW7CGULkzHHuzu4P0dGeVEXQU=; b=XTNtXqZoOfLSm5SCPUQot61YByw01oAdd6yFO/vOXv+/EwYLy1tNUdTuggZ/mgVGV2EH Z2yQlRBTQEH6dZvXJcif3qAxlmNPkdgU9V37Uy0DgjSc4WgCSX9EjiE30aTpJUhf04tA8 mAx6pcDwM0bgqH69YAlEn9hcV1T4Yn7MUD9Haxezv3IWPfxqwLurEF6+L4Nm6GK5FI4mF gp+IcfTYanAhyx4b63gy/+MMAI2RUyeBnvX4uFw0WlV5KABIteBUQFu0ryEWNTH3DN3GW hccNvds4bagMblEnLYekqWQFt0k1RpVW6jdTXwa3OX5d+ly2GAvrL4KD6+V5qcbeprg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=kzCjHtqG; 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 80D89606D49D; Fri, 13 Nov 2026 17:38:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=kzCjHtqG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D66F1F000C4; Fri, 13 Nov 2026 17:38:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794591525; bh=RoUA1KIcSQAwTa7CT6jW7CGULkzHHuzu4P0dGeVEXQU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kzCjHtqGmubqVtEn70O42F+fVxta3IaPUm3RenoQVRgihD5xmEFq5Fg03GWsBzLZl jUzfYFYEXHzNFvR0PVKqtDxauMYMeRc2rqcI2IlvPjcH0fny2igUhp1bEfG452zyIN AMZnQBiPmLP3hupa3LvgFXANjpzrhkFWKgs0JoGk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Takashi Iwai , Sasha Levin Subject: [PATCH 6.12 583/670] ALSA: emux: Fix UAF of soundfont zones at note-on Date: Fri, 13 Nov 2026 10:52:27 -0500 Message-ID: <20261113153831.595463116@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai [ Upstream commit 34e3e04b8a1731a773797542f0781e99ce7cd755 ] 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 Signed-off-by: Sasha Levin --- 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 b3c8296840a56..537a7c47ef475 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 18a919d1cdb64..ad4a0f262afa5 100644 --- a/sound/synth/emux/soundfont.c +++ b/sound/synth/emux/soundfont.c @@ -1264,6 +1264,9 @@ 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, @@ -1273,11 +1276,11 @@ 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