On 07/12/2017 02:51 AM, lixiubo@xxxxxxxxxxxxxxxxxxxx wrote:
> From: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
>
> For most case the sg->length equals to PAGE_SIZE, so this bug won't
> be triggered. Otherwise this will crash the kernel, for example when
> all segments' sg->length equal to 1K.
>
> Signed-off-by: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_user.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
> index 8bf0823..9030c2a 100644
> --- a/drivers/target/target_core_user.c
> +++ b/drivers/target/target_core_user.c
> @@ -590,8 +590,6 @@ static int scatter_data_area(struct tcmu_dev *udev,
> block_remaining);
> to_offset = get_block_offset_user(udev, dbi,
> block_remaining);
> - offset = DATA_BLOCK_SIZE - block_remaining;
> - to += offset;
>
> if (*iov_cnt != 0 &&
> to_offset == iov_tail(*iov)) {
> @@ -602,8 +600,10 @@ static int scatter_data_area(struct tcmu_dev *udev,
> (*iov)->iov_len = copy_bytes;
> }
> if (copy_data) {
> - memcpy(to, from + sg->length - sg_remaining,
> - copy_bytes);
> + offset = DATA_BLOCK_SIZE - block_remaining;
> + memcpy(to + offset,
> + from + sg->length - sg_remaining,
> + copy_bytes);
> tcmu_flush_dcache_range(to, copy_bytes);
> }
> sg_remaining -= copy_bytes;
> @@ -664,9 +664,8 @@ static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
> copy_bytes = min_t(size_t, sg_remaining,
> block_remaining);
> offset = DATA_BLOCK_SIZE - block_remaining;
> - from += offset;
> tcmu_flush_dcache_range(from, copy_bytes);
> - memcpy(to + sg->length - sg_remaining, from,
> + memcpy(to + sg->length - sg_remaining, from + offset,
> copy_bytes);
>
> sg_remaining -= copy_bytes;
>
Nice.
Reviewed-by: Mike Christie <mchristi@xxxxxxxxxx>
