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[195.14.217.60]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47ff79a7302sm8263913f8f.1.2026.08.06.10.47.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 10:47:30 -0700 (PDT) From: Vasileios Almpanis Date: Thu, 06 Aug 2026 19:47:22 +0200 Subject: [PATCH] media: dw2102: fix OOB read on firmware size not a multiple of 64 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260806-dvb-v1-1-a750f8e5b2ea@gmail.com> X-B4-Tracking: v=1; b=H4sIAKnIdGoC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIzMDCwMz3ZSyJF1jA3NzQ5O0NDMjI1MloMqCotS0zAqwKdGxEH5xaVJWanI JSKtSbS0Adwl+kGcAAAA= X-Change-ID: 20260806-dvb-307714ff6225 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, Vasileios Almpanis X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1786038450; l=2387; i=vasilisalmpanis@gmail.com; s=20260731; h=from:subject:message-id; bh=vSerB2OK/jOeZe0W9kGwcf0dSFaiMJU+D8sgcEwDWkI=; b=ForF2kxJMOHk+Qjpdztm/ba78RcPkxgtj1+6qk1gYPfpwvIjQK3I8tqD5pf9VyKCG1ZWtGVq4 m0j4UXCSLZlCCRuva1qlsiUSkmRglJOxoR08anD4wGBPtwBRA8vG0QK X-Developer-Key: i=vasilisalmpanis@gmail.com; a=ed25519; pk=gn5Uo6yL8Tlpq5uATxA3nqoq+U8eWLRbjD+bOk0qSpU= 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; 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