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([2402:e280:3d9e:537:8ccb:550c:e84d:a5b1]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b111adasm80657165ad.18.2025.11.22.01.31.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 22 Nov 2025 01:31:02 -0800 (PST) From: Sameeksha Sankpal To: mchehab@kernel.org Cc: christophe.jaillet@wanadoo.fr, hverkuil@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sameeksha Sankpal , syzbot+a83ee2dae0e6cc6cd3aa@syzkaller.appspotmail.com Subject: [PATCH] media: dtv5100: fix buffer overflow in dtv5100_i2c_msg() Date: Sat, 22 Nov 2025 15:00:56 +0530 Message-ID: <20251122093056.50774-1-sameekshasankpal@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" syzbot reported a field-spanning write where rlen (4096 bytes) is copied into st->data, which is only 80 bytes in size. This causes a buffer overflow and triggers KASAN warnings. Clamp the copy size using min_t() to ensure we never write beyond the bounds of st->data, and pass the clamped size to usb_control_msg(). This fixes the following syzbot report: Reported-by: syzbot+a83ee2dae0e6cc6cd3aa@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Da83ee2dae0e6cc6cd3aa Signed-off-by: Sameeksha Sankpal --- drivers/media/usb/dvb-usb/dtv5100.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/media/usb/dvb-usb/dtv5100.c b/drivers/media/usb/dvb-us= b/dtv5100.c index 3d85c6f7f6ec..df1ce9b49ecf 100644 --- a/drivers/media/usb/dvb-usb/dtv5100.c +++ b/drivers/media/usb/dvb-usb/dtv5100.c @@ -55,10 +55,13 @@ static int dtv5100_i2c_msg(struct dvb_usb_device *d, u8= addr, } index =3D (addr << 8) + wbuf[0]; =20 - memcpy(st->data, rbuf, rlen); + /* Prevent buffer overflow: st->data is 80 bytes */ + size_t copy_len =3D min_t(size_t, rlen, sizeof(st->data)); + + memcpy(st->data, rbuf, copy_len); msleep(1); /* avoid I2C errors */ return usb_control_msg(d->udev, pipe, request, - type, value, index, st->data, rlen, + type, value, index, st->data, copy_len, DTV5100_USB_TIMEOUT); } =20 --=20 2.43.0