| Message ID | YueoPDOseM1BGiXD@kili (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b8c0aa9b16bb2f4d5966b87fbf1f36f3280e1f60 |
| Headers | show |
| Series | [1/2] NTB: EPF: Fix error code in epf_ntb_bind() | expand |
On Mon, Aug 1, 2022 at 3:47 PM Dan Carpenter <dan.carpenter@oracle.com> wrote: > > 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> > --- > 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 cf338f3cf348..a7fe86f43739 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) { \ This might change the existing logic. will it be ? if (win_no <= 0 || win_no >= ntb->num_mws) { > dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \ > return -EINVAL; \ > } \ > -- > 2.35.1 >
On Tue, Aug 02, 2022 at 04:19:33PM +0530, Souptick Joarder wrote: > On Mon, Aug 1, 2022 at 3:47 PM Dan Carpenter <dan.carpenter@oracle.com> wrote: > > > > 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> > > --- > > 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 cf338f3cf348..a7fe86f43739 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) { \ > > This might change the existing logic. will it be ? > if (win_no <= 0 || win_no >= ntb->num_mws) { No, it doesn't change the exiting logic with regards to the upper bounds. if (foo > bar) is the same as if (bar < foo). It just adds a lower bounds check. Normally, the variable part of the condition is on the right. Check patch enforces that rule where it can. It's the same in English, the variable comes first. "If twelve foot is greater than the height of the tree then blah blah" vs "if the tree is less than twelve foot blah blah". regards, dan carpenter
On Tue, Aug 02, 2022 at 02:01:33PM +0300, Dan Carpenter wrote: > It's the same in English, the variable comes first. "If twelve foot > is greater than the height of the tree then blah blah" vs "if the tree > is less than twelve foot blah blah". Hehe... I had a brief momement of panic where I worried that these statements might not be equivalent. The backwards if is so confusing. regards, dan carpenter
On Tue, Aug 2, 2022 at 4:50 PM Dan Carpenter <dan.carpenter@oracle.com> wrote: > > On Tue, Aug 02, 2022 at 02:01:33PM +0300, Dan Carpenter wrote: > > It's the same in English, the variable comes first. "If twelve foot > > is greater than the height of the tree then blah blah" vs "if the tree > > is less than twelve foot blah blah". > > Hehe... I had a brief momement of panic where I worried that these > statements might not be equivalent. The backwards if is so confusing. hehe.. Sorry I read the condition wrong with an example value at first. Acked-by: Souptick Joarder (HPE) <jrdr.linux@gmail.com> > > regards, > dan carpenter
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c index cf338f3cf348..a7fe86f43739 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; \ } \
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> --- drivers/pci/endpoint/functions/pci-epf-vntb.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)