On Sat, Mar 28, 2020 at 08:30:40AM +0100, Christophe JAILLET wrote:
> There is an off-by-one issue when checking if there is enough space in the
> output buffer, because we must keep some place for a final '\0'.
>
> While at it:
> - Use 'scnprintf' instead of 'snprintf' in order to avoid a superfluous
> 'strlen'
> - avoid some useless initializations
> - avoida hard coded buffer size that can be computed at built time.
>
> Fixes: a51f06e1679e ("RDMA/ocrdma: Query controller information")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> ---
> The '\0' comes from memset(..., 0, ...) in all callers.
> This could be also avoided if needed.
> ---
> drivers/infiniband/hw/ocrdma/ocrdma_stats.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/infiniband/hw/ocrdma/ocrdma_stats.c b/drivers/infiniband/hw/ocrdma/ocrdma_stats.c
> index 5f831e3bdbad..614a449e6b87 100644
> --- a/drivers/infiniband/hw/ocrdma/ocrdma_stats.c
> +++ b/drivers/infiniband/hw/ocrdma/ocrdma_stats.c
> @@ -49,13 +49,12 @@ static struct dentry *ocrdma_dbgfs_dir;
> static int ocrdma_add_stat(char *start, char *pcur,
> char *name, u64 count)
> {
> - char buff[128] = {0};
> - int cpy_len = 0;
> + char buff[128];
> + int cpy_len;
>
> - snprintf(buff, 128, "%s: %llu\n", name, count);
> - cpy_len = strlen(buff);
> + cpy_len = scnprintf(buff, sizeof(buff), "%s: %llu\n", name, count);
>
> - if (pcur + cpy_len > start + OCRDMA_MAX_DBGFS_MEM) {
> + if (pcur + cpy_len >= start + OCRDMA_MAX_DBGFS_MEM) {
> pr_err("%s: No space in stats buff\n", __func__);
> return 0;
> }
The memcpy is still kind of silly right? What about this:
static int ocrdma_add_stat(char *start, char *pcur, char *name, u64 count)
{
size_t len = (start + OCRDMA_MAX_DBGFS_MEM) - pcur;
int cpy_len;
cpy_len = snprintf(pcur, len, "%s: %llu\n", name, count);
if (cpy_len >= len || cpy_len < 0) {
pr_err("%s: No space in stats buff\n", __func__);
return 0;
}
return cpy_len;
}
Jason
