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=1793063390; b=PKnVj24gfpdbKeCfllJ0s86W9q76LwrvsImZVWuU1En+q2WN4abBk2gXVtVfbfNpmUls 0qmexvEtqGHLWEK/2eoZLox7RMUJdaNT+WWas1DXVm2Kr1V6UGdLkFPahPdT9+DvjjY2B +AhW+iEGeYYiAQRM+m+H4uAfuhdmcZ2xJyXF7KVWCucVHf07dq5tmQG8UlG0i56TgIXJ2 N0PeJB1rtSR90n/V6xyHSy02SJez4o6eqKNR3yzq9pkD0Msl+3rg7X5U27IaeALnIH6vS DbPcINGB1zw58T7sMfBLgn1RNK1gt5TkZVvG9/ldBZtvb5Hf/cyDvz7rtubjdmWvwFA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793063390; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: In-Reply-To:References:X-Mailer:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=xvbMHvz44q6egU6UHmyrVq7TTu1E+YqD75Q/63ez7/E=; b=QwMFUgi+vx4G4JfIE0FsKmGIccMoFAwXjMDUJMakkfSHkTguww/fFYmEAtGw3fKvd+U6 SnvFCWYGPeIwP1fi5B8homEUmuHS98v6MrKUuSPqyUvwFiNN2DeXDuO3TZwyDrHyJqoaS +uZ19SjnfLXdiI7wfBTPwrg6RTSkOdwemtKJsHDdEX9Ov9bBwWvaCG6/axmWvNF+Oqr3j kw1vIRqwWswW3075Fhsc0OTMwiEPxt8C0o/5jlv8rQigJsclKHC0IJTlK/d/7EW7J1TkC HYYzN/qutQbB7oOELiIWw9uWttK7Bpo490SJIP0OoyRWUDG1IyHzWn1rKkjLO2qz6fA== 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=Lo0Ng5hz; 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 AE52F606A31A; Tue, 27 Oct 2026 01:09:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Lo0Ng5hz Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72D781F01825; Tue, 27 Oct 2026 01:09:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793063389; bh=xvbMHvz44q6egU6UHmyrVq7TTu1E+YqD75Q/63ez7/E=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=Lo0Ng5hz8D5+SDQAjVUXEG5RLC5UI/0jmIzSkgDXLA5n5GAHaW8Oh1aTN4hjv+4Kk rkwRMMVR3PMQ/DWSQeqfhIkm5ZquVb1v1P4e7SoVZ0uXBU/byB1X9Kt2C74RtAeE95 qWssxbEj4By1bw4wQhiU8+RyzNFZFlx78nfKZLMYaKe5X5+aKXmBfGLAfVXjvSJ467 V4+i3BPf7oL6NoXervU+TGZvFJj+GgdcitMPhHXPDJI4qF+HGihS3yfYBf9FTDVigf P0ouiL73T13nx31OGf6HGJVf5eGK5H/Yf8zxbQanMAMIa1wZ+Y8BOMVmfy1mOyGIub M0vzk6bc7TRxQ== Date: Tue, 27 Oct 2026 01:09:40 +0000 From: Jonathan Cameron To: Tristan Madani Cc: Marius Cristea , David Lechner , Nuno Sa , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, tristan@talencesecurity.com Subject: Re: [PATCH] iio: adc: pac1934: validate ACPI _DSM return type and bounds Message-ID: <20261027010940.50bd884a@jic23-hlaptop> In-Reply-To: <20261026230910.2569782-1-tristan@talencesecurity.com> References: <20261026230910.2569782-1-tristan@talencesecurity.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) X-Mailing-List: linux-kernel@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=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 26 Oct 2026 23:09:10 +0000 Tristan Madani wrote: > pac1934_acpi_parse_channel_config() calls acpi_evaluate_dsm() four > times to read channel configuration but does not validate the returned > object type or array bounds: > > 1. No check that the returned object is ACPI_TYPE_PACKAGE. If > firmware returns a different type, accessing rez->package.count > and rez->package.elements on a non-package object produces > unpredictable values. > > 2. The loop bounds use rez->package.count directly without capping > to PAC1934_MAX_NUM_CHANNELS (4). A package with more elements > than expected causes writes past the fixed-size labels[], > shunts[], and active_channels[] arrays. > > 3. The bipolar and sample rate DSM calls access elements[0] without > verifying package.count >= 1. > > Add ACPI_TYPE_PACKAGE validation after each acpi_evaluate_dsm() call, > cap loop iterations to PAC1934_MAX_NUM_CHANNELS, and verify package > count >= 1 before accessing elements[0]. > > Fixes: 0fb528c8255b ("iio: adc: adding support for PAC193x") I should have mentioned this for earlier patches. This is to my eyes not a fix, it is hardening against buggy firmware. Now I'm fine with doing such hardening but we don't want to suggest it is something folk should definitely backport. > Cc: stable@vger.kernel.org > Signed-off-by: Tristan Madani > --- > drivers/iio/adc/pac1934.c | 23 +++++++++++++++++++++-- > 1 file changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c > index de59dc27c4405..43c4705c27be7 100644 > --- a/drivers/iio/adc/pac1934.c > +++ b/drivers/iio/adc/pac1934.c > @@ -1101,8 +1101,13 @@ static int pac1934_acpi_parse_channel_config(struct i2c_client *client, > rez = acpi_evaluate_dsm(handle, &guid, 0, PAC1934_ACPI_GET_NAMES_AND_MOHMS_VALS, NULL); > if (!rez) > return -EINVAL; > + if (rez->type != ACPI_TYPE_PACKAGE) { > + ACPI_FREE(rez); > + return -EINVAL; > + } > > - for (i = 0; i < rez->package.count; i += 2) { > + for (i = 0; i + 1 < rez->package.count && > + i / 2 < PAC1934_MAX_NUM_CHANNELS; i += 2) { > idx = i / 2; > info->labels[idx] = > devm_kmemdup(dev, rez->package.elements[i].string.pointer, > @@ -1130,7 +1135,13 @@ static int pac1934_acpi_parse_channel_config(struct i2c_client *client, > return 0; > } > > - for (i = 0; i < rez->package.count; i++) { > + if (rez->type != ACPI_TYPE_PACKAGE) { > + ACPI_FREE(rez); > + return -EINVAL; > + } > + > + for (i = 0; i < rez->package.count && > + i < PAC1934_MAX_NUM_CHANNELS; i++) { > idx = i; > info->shunts[idx] = rez->package.elements[i].integer.value; > info->active_channels[idx] = (info->shunts[idx] != 0); > @@ -1141,6 +1152,10 @@ static int pac1934_acpi_parse_channel_config(struct i2c_client *client, > rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_BIPOLAR_SETTINGS, NULL); > if (!rez) > return -EINVAL; > + if (rez->type != ACPI_TYPE_PACKAGE || rez->package.count < 1) { > + ACPI_FREE(rez); > + return -EINVAL; > + } > > bi_dir_mask = rez->package.elements[0].integer.value; > info->bi_dir[0] = ((bi_dir_mask & (1 << 3)) | (bi_dir_mask & (1 << 7))) != 0; > @@ -1153,6 +1168,10 @@ static int pac1934_acpi_parse_channel_config(struct i2c_client *client, > rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_SAMP, NULL); > if (!rez) > return -EINVAL; > + if (rez->type != ACPI_TYPE_PACKAGE || rez->package.count < 1) { > + ACPI_FREE(rez); > + return -EINVAL; > + } > > info->sample_rate_value = rez->package.elements[0].integer.value; >