From 42aafd8b48adac1c3b20fe5892b1b91b80c1a1e6 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 16 Oct 2024 21:48:47 +0800 Subject: ublk: don't allow user copy for unprivileged device UBLK_F_USER_COPY requires userspace to call write() on ublk char device for filling request buffer, and unprivileged device can't be trusted. So don't allow user copy for unprivileged device. Cc: stable@vger.kernel.org Fixes: 1172d5b8beca ("ublk: support user copy") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20241016134847.2911721-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- include/uapi/linux/ublk_cmd.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/uapi') diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index c8dc5f8ea699..12873639ea96 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -175,7 +175,13 @@ /* use ioctl encoding for uring command */ #define UBLK_F_CMD_IOCTL_ENCODE (1UL << 6) -/* Copy between request and user buffer by pread()/pwrite() */ +/* + * Copy between request and user buffer by pread()/pwrite() + * + * Not available for UBLK_F_UNPRIVILEGED_DEV, otherwise userspace may + * deceive us by not filling request buffer, then kernel uninitialized + * data may be leaked. + */ #define UBLK_F_USER_COPY (1UL << 7) /* -- cgit v1.2.3-73-gaa49b