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[195.14.217.60]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-480021506desm3865582f8f.10.2026.08.07.01.46.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 07 Aug 2026 01:46:41 -0700 (PDT) Message-ID: <576fd334-3482-4ada-9b35-2e67a024e306@gmail.com> Date: Fri, 7 Aug 2026 10:46:40 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] media: dw2102: fix OOB read on firmware size not a multiple of 64 To: Mauro Carvalho Chehab , Igor M Liplianin Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+f408eac9faa61d5a1927@syzkaller.appspotmail.com References: <20260806-dvb-v1-1-a750f8e5b2ea@gmail.com> Content-Language: en-US From: Vasileios Almpanis In-Reply-To: <20260806-dvb-v1-1-a750f8e5b2ea@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/6/26 7:47 PM, Vasileios Almpanis wrote: > dw2102_load_firmware() copies the firmware into a buffer of exactly > fw->size bytes, then walks it in 0x40-byte steps while always passing > 0x40 as the transfer length. When fw->size is not a multiple of 64 the > last chunk reads past the end of the allocation producing the following > splat: > > dvb-usb: downloading firmware from file 'dvb-usb-dw3101.fw' > dw2102: start downloading DW210X firmware > ================================================================== > BUG: KASAN: slab-out-of-bounds in dw210x_op_rw+0xb6/0x180 drivers/media/usb/dvb-usb/dw2102.c:102 > Read of size 64 at addr ffff88802bcf2ba0 by task kworker/1:2/803 > Call Trace: > > kasan_report+0x117/0x150 mm/kasan/report.c:595 > check_region_inline mm/kasan/generic.c:-1 [inline] > kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200 > __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105 > dw210x_op_rw+0xb6/0x180 drivers/media/usb/dvb-usb/dw2102.c:102 > dw2102_load_firmware+0x2b4/0x970 drivers/media/usb/dvb-usb/dw2102.c:1906 > > Fix this by clamping the last chunk to the remaining bytes; I sent this patch to syzbot for testing and it reported success. https://syzkaller.appspot.com/bug?extid=f408eac9faa61d5a1927 Tested-by: syzbot+f408eac9faa61d5a1927@syzkaller.appspotmail.com > Cc: stable@vger.kernel.org > Reported-by: syzbot+f408eac9faa61d5a1927@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=f408eac9faa61d5a1927 > Fixes: 7fd4828f6cc5 ("V4L/DVB (8421): Adds support for Dvbworld DVB-S 2102 USB card") > Signed-off-by: Vasileios Almpanis > --- > drivers/media/usb/dvb-usb/dw2102.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/usb/dvb-usb/dw2102.c b/drivers/media/usb/dvb-usb/dw2102.c > index 4fecf2f965e9..4e26e1776977 100644 > --- a/drivers/media/usb/dvb-usb/dw2102.c > +++ b/drivers/media/usb/dvb-usb/dw2102.c > @@ -1902,9 +1902,11 @@ static int dw2102_load_firmware(struct usb_device *dev, > if (p) { > memcpy(p, fw->data, fw->size); > for (i = 0; i < fw->size; i += 0x40) { > + int len = min_t(size_t, fw->size - i, 0x40); > + > b = (u8 *)p + i; > - if (dw210x_op_rw(dev, 0xa0, i, 0, b, 0x40, > - DW210X_WRITE_MSG) != 0x40) { > + if (dw210x_op_rw(dev, 0xa0, i, 0, b, len, > + DW210X_WRITE_MSG) != len) { > err("error while transferring firmware"); > ret = -EINVAL; > break; > > --- > base-commit: fcaeecb8b0cd44f77d03b28de0671258d4db18f8 > change-id: 20260806-dvb-307714ff6225 > > Best regards, > -- > Vasileios Almpanis >