From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BCB092D0C94; Sat, 12 Sep 2026 19:35:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789241717; cv=none; b=UetBIZhei42TgPdy2g+AxtMm4Fihm5t8OyXGws/b6ntkUpCBRHQmUZTs2xVuSbFyL3zUyV53XCcDUN/iteHXBsosPiCtf3/MQcQT3Fn3igxU3N7h+VeWPAQmFjA1LFMfw3I9Hx4svxFOMbG6R8fp/AkkL28FZCNS1gWys5aMcLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789241717; c=relaxed/simple; bh=/69LN+y7tIRUvv+UxHOePhoYgHscpepqG1Qk8zuDyM0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MsC2h7B2BCWZexkdzx8x2ClzbENoEvQRG7r8M/V+SmuzqQuHA2Y4dErnNftZSzyg9MKiRqvnlq8k1bcSsshesSwxn5vLrYH2u7S6fL4XINVWToWwAEG7SOGiuOAxE1Pi8Q5jrhMpoOr2pZnrT3qoDMpfAW3Nkc31YcN/Mdn6vlw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rMkd2cgD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rMkd2cgD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66F651F000FF; Sat, 12 Sep 2026 19:35:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789241716; bh=R/5hPZ3iqkzOgEb0wsxJBycvbGIm9GjAScXZxHmt+Ls=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rMkd2cgDKSekaxmnEuAobTujkgkinSae+8Pjqe2Wcu2XvXatCHOAYvVrHm7SAdWzY cpSbV8peijWdOjwezE4XIQqVL7lAfft9aYjvkJ6zKEZRa4m/jkXzH3Dvax3ta3KRCm YOKCJUl77IN4OXWSo2OzAV8NNvQl6I+m5A1nsodk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sonali Pradhan , Sasha Levin Subject: [PATCH 5.10 191/798] usb: gadget: u_audio: Fix use-after-free on sound card disconnect Date: Sat, 12 Sep 2026 08:56:59 +0200 Message-ID: <20260912065521.434289865@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065516.948645775@linuxfoundation.org> References: <20260912065516.948645775@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sonali Pradhan commit 858965947081d10d41d9a1010a540d3d5eea958b upstream. g_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound card teardown and immediately frees the underlying struct snd_uac_chip context. However, snd_card_free_when_closed() returns asynchronously while ALSA control elements (kctls) remain open in userspace. When userspace control applications access or close these open file descriptors, kctl callbacks attempt to dereference kctl->private_data pointing to &uac->c_prm or &uac->p_prm within the freed uac structure, resulting in a use-after-free (UAF) memory corruption. Fix this issue by deferring the destruction of struct snd_uac_chip until all references to the ALSA sound card are released. Register a custom card->private_free callback (u_audio_card_free) during g_audio_setup() that frees uac and its associated playback/capture request and ring buffers only when the sound card reference count drops to zero. Fixes: 6c67ed9ad9b8 ("usb: gadget: u_audio: don't let userspace block driver unbind") Cc: stable@vger.kernel.org Signed-off-by: Sonali Pradhan Link: https://patch.msgid.link/20260810071237.2207680-1-sonalipradhan@google.com Signed-off-by: Greg Kroah-Hartman [sonalipradhan: resolved ureq field naming and placement conflicts for 5.10-stable] Signed-off-by: Sonali Pradhan Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_audio.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c index a387ff2c8b730..2d190d6f628c3 100644 --- a/drivers/usb/gadget/function/u_audio.c +++ b/drivers/usb/gadget/function/u_audio.c @@ -486,6 +486,20 @@ void u_audio_stop_playback(struct g_audio *audio_dev) } EXPORT_SYMBOL_GPL(u_audio_stop_playback); +static void u_audio_card_free(struct snd_card *card) +{ + struct snd_uac_chip *uac = card->private_data; + + if (!uac) + return; + + kfree(uac->p_prm.ureq); + kfree(uac->c_prm.ureq); + kfree(uac->p_prm.rbuf); + kfree(uac->c_prm.rbuf); + kfree(uac); +} + int g_audio_setup(struct g_audio *g_audio, const char *pcm_name, const char *card_name) { @@ -560,6 +574,8 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name, goto fail; uac->card = card; + card->private_data = uac; + card->private_free = u_audio_card_free; /* * Create first PCM device @@ -591,6 +607,8 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name, snd_fail: snd_card_free(card); + return err; + fail: kfree(uac->p_prm.ureq); kfree(uac->c_prm.ureq); @@ -616,12 +634,6 @@ void g_audio_cleanup(struct g_audio *g_audio) card = uac->card; if (card) snd_card_free_when_closed(card); - - kfree(uac->p_prm.ureq); - kfree(uac->c_prm.ureq); - kfree(uac->p_prm.rbuf); - kfree(uac->c_prm.rbuf); - kfree(uac); } EXPORT_SYMBOL_GPL(g_audio_cleanup); -- 2.53.0