[PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp_verify()

[PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp_verify()

[Dan Carpenter]

The "chan" value comes from the user via sysfs.  A large like UINT_MAX
could overflow the buffer by three bytes.  Make the buffer larger and
use snprintf() instead of sprintf().

Fixes: 1aa66a3a135a ("ptp: ocp: Program the signal generators via PTP_CLK_REQ_PEROUT")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/ptp/ptp_ocp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 56b04a7bba3a..f0565c4a85df 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -968,15 +968,15 @@ ptp_ocp_verify(struct ptp_clock_info *ptp_info, unsigned pin,
 	       enum ptp_pin_function func, unsigned chan)
 {
 	struct ptp_ocp *bp = container_of(ptp_info, struct ptp_ocp, ptp_info);
-	char buf[16];
+	char buf[20];
 
 	if (func != PTP_PF_PEROUT)
 		return -EOPNOTSUPP;
 
 	if (chan)
-		sprintf(buf, "OUT: GEN%d", chan);
+		snprintf(buf, sizeof(buf), "OUT: GEN%d", chan);
 	else
-		sprintf(buf, "OUT: PHC");
+		snprintf(buf, sizeof(buf), "OUT: PHC");
 
 	return ptp_ocp_sma_store(bp, buf, pin + 1);
 }
-- 
2.20.1

Re: [PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp_verify()

[Jonathan Lemon]

On Thu, Mar 17, 2022 at 10:59:57AM +0300, Dan Carpenter wrote:
> The "chan" value comes from the user via sysfs.  A large like UINT_MAX
> could overflow the buffer by three bytes.  Make the buffer larger and
> use snprintf() instead of sprintf().
> 
> Fixes: 1aa66a3a135a ("ptp: ocp: Program the signal generators via PTP_CLK_REQ_PEROUT")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

This needs to be respun to catch up with the last patch.
-- 
Jonathan

Re: [PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp_verify()

[Dan Carpenter]

On Thu, Mar 17, 2022 at 10:04:49AM -0700, Jonathan Lemon wrote:
> On Thu, Mar 17, 2022 at 10:59:57AM +0300, Dan Carpenter wrote:
> > The "chan" value comes from the user via sysfs.  A large like UINT_MAX
> > could overflow the buffer by three bytes.  Make the buffer larger and
> > use snprintf() instead of sprintf().
> > 
> > Fixes: 1aa66a3a135a ("ptp: ocp: Program the signal generators via PTP_CLK_REQ_PEROUT")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> This needs to be respun to catch up with the last patch.

Thanks.  It turns out you can't actually trigger this bug.  Still using
snprintf() is better so I will resend.

regards,
dan carpenter