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Sun, 11 May 2025 14:27:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746973639; bh=qYsPB5KTJZb+XUGm4MW6ZwKZMh54o71O1hC+tg3tZWI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VUTFGZsfLBrHnjVnBTeej4wSPZzyPI6+32RY1g9O8Wgdp865wvZgZqUP6ZUvCJDST OW9a5RdYmOw53EABLcl+/LFqcmiT5iL1+avGUChdgS2gHQHfczML3CrO2wTkJ8rz6F CMazwxn5m+RtnpAo+K7dg0TAGowB8SZaK9LQU5Q11spR3ShzejqeaPM7SnJ1szITOY sCNQW1pmzbbK6k2NgqwrqJMvUQ4TPg3TVB67TVoslAlYYSSfXXssVHNG27CZLSPrLb 3MWWCAShtdXDHPI9siix40h2m2Xw1ef67f7pd8l4hEffQk+2J/CmA2n9AKwsqWUYnu zICK5ZaW1dXtg== Date: Sun, 11 May 2025 15:27:07 +0100 From: Jonathan Cameron To: Markus Burri Cc: linux-kernel@vger.kernel.org, Mahesh J Salgaonkar , "Oliver O'Halloran" , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Jacek Lawrynowicz , Maciej Falkowski , Oded Gabbay , Linus Walleij , Bartosz Golaszewski , Nuno Sa , Olivier Moysan , Lars-Peter Clausen , linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org, linux-gpio@vger.kernel.org, linux-iio@vger.kernel.org, Markus Burri Subject: Re: [PATCH v4 1/6] iio: backend: fix out-of-bound write Message-ID: <20250511152707.294bc7b9@jic23-huawei> In-Reply-To: <20250508130612.82270-2-markus.burri@mt.com> References: <20250508130612.82270-1-markus.burri@mt.com> <20250508130612.82270-2-markus.burri@mt.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.48; x86_64-pc-linux-gnu) X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 8 May 2025 15:06:07 +0200 Markus Burri wrote: > The buffer is set to 80 character. If a caller write more characters, > count is truncated to the max available space in "simple_write_to_buffer". > But afterwards a string terminator is written to the buffer at offset count > without boundary check. The zero termination is written OUT-OF-BOUND. > > Add a check that the given buffer is smaller then the buffer to prevent. > > Fixes: 035b4989211d ("iio: backend: make sure to NULL terminate stack buffer") > Signed-off-by: Markus Burri I'm looking for a tag from Nuno on this one before applying. J > --- > drivers/iio/industrialio-backend.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c > index a43c8d1bb3d0..31fe793e345e 100644 > --- a/drivers/iio/industrialio-backend.c > +++ b/drivers/iio/industrialio-backend.c > @@ -155,11 +155,14 @@ static ssize_t iio_backend_debugfs_write_reg(struct file *file, > ssize_t rc; > int ret; > > + if (count >= sizeof(buf)) > + return -ENOSPC; > + > rc = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf, count); > if (rc < 0) > return rc; > > - buf[count] = '\0'; > + buf[rc] = '\0'; > > ret = sscanf(buf, "%i %i", &back->cached_reg_addr, &val); >