[net-next,1/5] ptp: clockmatrix: bug fix for idtcm_strverscmp

Commit Message

Min Li Nov. 16, 2020, 7:27 p.m. UTC

From: Min Li <[e-mail]>

Feed kstrtou8 with NULL terminated string.

Signed-off-by: Min Li <[e-mail]>
---
 drivers/ptp/ptp_clockmatrix.c | 52 +++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 14 deletions(-)

Comments

Jakub Kicinski Nov. 17, 2020, 1:27 a.m. UTC | #1

On Mon, 16 Nov 2020 14:27:26 -0500 [e-mail] wrote:
> From: Min Li <[e-mail]>
> 
> Feed kstrtou8 with NULL terminated string.

Is this a fix? Does it need to be backported to stable?

Also please add a cover letter for the series describing the overall
goal of this work, what testing has been done etc.

>  drivers/ptp/ptp_clockmatrix.c | 52 +++++++++++++++++++++++++++++++------------
>  1 file changed, 38 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/ptp/ptp_clockmatrix.c b/drivers/ptp/ptp_clockmatrix.c
> index e020faf..bf2be50 100644
> --- a/drivers/ptp/ptp_clockmatrix.c
> +++ b/drivers/ptp/ptp_clockmatrix.c
> @@ -103,42 +103,66 @@ static int timespec_to_char_array(struct timespec64 const *ts,
>  	return 0;
>  }
>  
> -static int idtcm_strverscmp(const char *ver1, const char *ver2)
> +static int idtcm_strverscmp(const char *version1, const char *version2)
>  {
>  	u8 num1;
>  	u8 num2;
>  	int result = 0;
> +	char ver1[16];
> +	char ver2[16];
> +	char *cur1;
> +	char *cur2;
> +	char *next1;
> +	char *next2;
> +
> +	strncpy(ver1, version1, 16);
> +	strncpy(ver2, version2, 16);

This patch triggers the following warning on a 32bit build:

In file included from ../arch/x86/include/asm/page_32.h:35,
                 from ../arch/x86/include/asm/page.h:14,
                 from ../arch/x86/include/asm/thread_info.h:12,
                 from ../include/linux/thread_info.h:38,
                 from ../arch/x86/include/asm/preempt.h:7,
                 from ../include/linux/preempt.h:78,
                 from ../include/linux/spinlock.h:51,
                 from ../include/linux/mmzone.h:8,
                 from ../include/linux/gfp.h:6,
                 from ../include/linux/firmware.h:7,
                 from ../drivers/ptp/ptp_clockmatrix.c:8:
In function ‘strncpy’,
    inlined from ‘idtcm_strverscmp.constprop’ at ../drivers/ptp/ptp_clockmatrix.c:118:2:
../include/linux/string.h:290:30: warning: ‘__builtin_strncpy’ specified bound 16 equals destination size [-Wstringop-truncation]
  290 | #define __underlying_strncpy __builtin_strncpy
      |                              ^
../include/linux/string.h:300:9: note: in expansion of macro ‘__underlying_strncpy’
  300 |  return __underlying_strncpy(p, q, size);
      |         ^~~~~~~~~~~~~~~~~~~~

Patch

diff --git a/drivers/ptp/ptp_clockmatrix.c b/drivers/ptp/ptp_clockmatrix.c
index e020faf..bf2be50 100644
--- a/drivers/ptp/ptp_clockmatrix.c
+++ b/drivers/ptp/ptp_clockmatrix.c
@@ -103,42 +103,66 @@  static int timespec_to_char_array(struct timespec64 const *ts,
 	return 0;
 }
 
-static int idtcm_strverscmp(const char *ver1, const char *ver2)
+static int idtcm_strverscmp(const char *version1, const char *version2)
 {
 	u8 num1;
 	u8 num2;
 	int result = 0;
+	char ver1[16];
+	char ver2[16];
+	char *cur1;
+	char *cur2;
+	char *next1;
+	char *next2;
+
+	strncpy(ver1, version1, 16);
+	strncpy(ver2, version2, 16);
+	cur1 = ver1;
+	cur2 = ver2;
 
 	/* loop through each level of the version string */
 	while (result == 0) {
+		next1 = strchr(cur1, '.');
+		next2 = strchr(cur2, '.');
+
+		/* kstrtou8 could fail for dot */
+		if (next1) {
+			*next1 = '\0';
+			next1++;
+		}
+
+		if (next2) {
+			*next2 = '\0';
+			next2++;
+		}
+
 		/* extract leading version numbers */
-		if (kstrtou8(ver1, 10, &num1) < 0)
+		if (kstrtou8(cur1, 10, &num1) < 0)
 			return -1;
 
-		if (kstrtou8(ver2, 10, &num2) < 0)
+		if (kstrtou8(cur2, 10, &num2) < 0)
 			return -1;
 
 		/* if numbers differ, then set the result */
-		if (num1 < num2)
+		if (num1 < num2) {
 			result = -1;
-		else if (num1 > num2)
+		} else if (num1 > num2) {
 			result = 1;
-		else {
+		} else {
 			/* if numbers are the same, go to next level */
-			ver1 = strchr(ver1, '.');
-			ver2 = strchr(ver2, '.');
-			if (!ver1 && !ver2)
+			if (!next1 && !next2)
 				break;
-			else if (!ver1)
+			else if (!next1) {
 				result = -1;
-			else if (!ver2)
+			} else if (!next2) {
 				result = 1;
-			else {
-				ver1++;
-				ver2++;
+			} else {
+				cur1 = next1;
+				cur2 = next2;
 			}
 		}
 	}
+
 	return result;
 }