From b8c0aa9b16bb2f4d5966b87fbf1f36f3280e1f60 Mon Sep 17 00:00:00 2001 From: Dan Carpenter <dan.carpenter@oracle.com> Date: Mon, 1 Aug 2022 13:17:32 +0300 Subject: NTB: EPF: Tidy up some bounds checks This sscanf() is reading from the filename which was set by the kernel so it should be trust worthy. Although the data is likely trust worthy there is some bounds checking but unfortunately, it is not complete or consistent. Additionally, the Smatch static checker marks everything that comes from sscanf() as tainted and so Smatch complains that this code can lead to an out of bounds issue. Let's clean things up and make Smatch happy. The first problem is that there is no bounds checking in the _show() functions. The _store() and _show() functions are very similar so make the bounds checking the same in both. The second issue is that if "win_no" is zero it leads to an array underflow so add an if (win_no <= 0) check for that. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Souptick Joarder (HPE) <jrdr.linux@gmail.com> Signed-off-by: Jon Mason <jdmason@kudzu.us> --- drivers/pci/endpoint/functions/pci-epf-vntb.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c index a5fa32eab39c..0ea85e1d292e 100644 --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c @@ -831,9 +831,16 @@ static ssize_t epf_ntb_##_name##_show(struct config_item *item, \ { \ struct config_group *group = to_config_group(item); \ struct epf_ntb *ntb = to_epf_ntb(group); \ + struct device *dev = &ntb->epf->dev; \ int win_no; \ \ - sscanf(#_name, "mw%d", &win_no); \ + if (sscanf(#_name, "mw%d", &win_no) != 1) \ + return -EINVAL; \ + \ + if (win_no <= 0 || win_no > ntb->num_mws) { \ + dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \ + return -EINVAL; \ + } \ \ return sprintf(page, "%lld\n", ntb->mws_size[win_no - 1]); \ } @@ -856,7 +863,7 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \ if (sscanf(#_name, "mw%d", &win_no) != 1) \ return -EINVAL; \ \ - if (ntb->num_mws < win_no) { \ + if (win_no <= 0 || win_no > ntb->num_mws) { \ dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \ return -EINVAL; \ } \ -- cgit v1.2.3-70-g09d2