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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id y21-20020a7bcd95000000b003fbb346279dsm3275702wmj.38.2023.08.18.08.58.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Aug 2023 08:58:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1692374329; x=1692979129; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Tt8gFXZAVgdSU8JxW7d1fDhLvNPeIviD1msZV2xcw/0=; b=N+simupBpQC/XNMuPjHaVTjvwF9Q5bN3vSU5CC15EUYwYKLzB9ltQr8cKJBWZN2LFV 7k71gTogBVFVAW/evF27LAF+9/Hcj2nOw0NfcERIhN9rze1cwLUjlTz0dLlMdbrLVsH6 BU1rkPegAWei2ocylJTtb6+GAMoBLraY7DI7J9PAttJNk++hjaP0XzRZV3gWoifBfN7z kQknWNx2DxI8XAznWDIMw0H/B10bq3Jae86KhKFc7rS+b/2e32mChg+UH58VFWwdUpvG OJlgVQ5J6VoOIOScvJpwT3SUS62xLoLNNDSl4aJQSw5bJInBfJHZW23LgddpYNsmsIT0 vwgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692374329; x=1692979129; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Tt8gFXZAVgdSU8JxW7d1fDhLvNPeIviD1msZV2xcw/0=; b=CLg6fS1Z2dlUh3lxr2JLXIB2XizDnP86VUq41CM8BxJsHMzwu9rQ3XseKWQGeXF6xI jYp7bmc02HDJep9BKy+jxh63a3wtQqSCQhsW+wybQRgeuGFCSE7UoFYQ+EFRgFpqy7RG Gtf5iEUZlh0dZouWyB41di+f93Pk38WLSRwsG9yAgOt28J4F4PL43mmikKKKsqWHbXTN qKbBWwx8P8oZDDAeY0dmDhlplyLJ7btGlLO2q/AcITc0wCzwDFxR3w/a3bRZD3jdDiPs jNIiWmpLunv3/POvyH46PscX6+Gw7cSEVGhGRX3MppWNlRY03TB/2VSeJmDKuj7WxKVB 5r0A== X-Gm-Message-State: AOJu0YxBRToDVKtvwAWlfL3dFm5Pts0O0sgb6CAp7ol/T80xRXztmbMk Ei4O3ny5D5ffjfTl3HW8glsvWbpH2DKvQ19932k= X-Google-Smtp-Source: AGHT+IHrRHQAa8psh6HkaX5DtFA1zBhnSH53y7d1O3vf6UXmyS3CdSOmIoDaAixhXM5u5J6Xa3raDQ== X-Received: by 2002:a7b:cb8e:0:b0:3f8:fc96:6bfd with SMTP id m14-20020a7bcb8e000000b003f8fc966bfdmr2461506wmi.17.1692374328768; Fri, 18 Aug 2023 08:58:48 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Cc: Gerd Hoffmann , Christian Schoenebeck Subject: [PATCH 2/2] audio/jackaudio: Avoid dynamic stack allocation in qjack_process() Date: Fri, 18 Aug 2023 16:58:46 +0100 Message-Id: <20230818155846.1651287-3-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230818155846.1651287-1-peter.maydell@linaro.org> References: <20230818155846.1651287-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::335; envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x335.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1692374352877100001 Content-Type: text/plain; charset="utf-8" Avoid a dynamic stack allocation in qjack_process(). Since this function is a JACK process callback, we are not permitted to malloc() here, so we allocate a working buffer in qjack_client_init() instead. The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). Signed-off-by: Peter Maydell Reviewed-by: Christian Schoenebeck Reviewed-by: Francisco Iglesias --- This feels like we ought to be able to say "we know there are at most X channels, so allocate an array of size X on the stack", but I couldn't find anything in the audio subsystem from a quick look that set an obvious bound on the number of channels. Is there some straightforward constant MAX_CHANNELS somewhere? --- audio/jackaudio.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/audio/jackaudio.c b/audio/jackaudio.c index 7cb2a49f971..e1eaa3477dc 100644 --- a/audio/jackaudio.c +++ b/audio/jackaudio.c @@ -70,6 +70,9 @@ typedef struct QJackClient { int buffersize; jack_port_t **port; QJackBuffer fifo; + + /* Used as workspace by qjack_process() */ + float **process_buffers; } QJackClient; =20 @@ -267,22 +270,21 @@ static int qjack_process(jack_nframes_t nframes, void= *arg) } =20 /* get the buffers for the ports */ - float *buffers[c->nchannels]; for (int i =3D 0; i < c->nchannels; ++i) { - buffers[i] =3D jack_port_get_buffer(c->port[i], nframes); + c->process_buffers[i] =3D jack_port_get_buffer(c->port[i], nframes= ); } =20 if (c->out) { if (likely(c->enabled)) { - qjack_buffer_read_l(&c->fifo, buffers, nframes); + qjack_buffer_read_l(&c->fifo, c->process_buffers, nframes); } else { for (int i =3D 0; i < c->nchannels; ++i) { - memset(buffers[i], 0, nframes * sizeof(float)); + memset(c->process_buffers[i], 0, nframes * sizeof(float)); } } } else { if (likely(c->enabled)) { - qjack_buffer_write_l(&c->fifo, buffers, nframes); + qjack_buffer_write_l(&c->fifo, c->process_buffers, nframes); } } =20 @@ -448,6 +450,9 @@ static int qjack_client_init(QJackClient *c) jack_get_client_name(c->client)); } =20 + /* Allocate working buffer for process callback */ + c->process_buffers =3D g_new(float *, c->nchannels); + jack_set_process_callback(c->client, qjack_process , c); jack_set_port_registration_callback(c->client, qjack_port_registration= , c); jack_set_xrun_callback(c->client, qjack_xrun, c); @@ -579,6 +584,7 @@ static void qjack_client_fini_locked(QJackClient *c) =20 qjack_buffer_free(&c->fifo); g_free(c->port); + g_free(c->process_buffers); =20 c->state =3D QJACK_STATE_DISCONNECTED; /* fallthrough */ --=20 2.34.1