From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Fri, 7 Oct 2022 12:35:37 -0500

Subject: [PATCH] libmultipath: cleanup remove_feature

remove_feature() didn't correctly handle feature strings that used

whitespace other than spaces, which the kernel allows. It also didn't

check if the feature string to be removed was part of a larger feature

token. Finally, it did a lot of unnecessary work. By failing if the

feature string to be removed contains leading or trailing whitespace,

the function can be significanly simplified.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

Reviewed-by: Martin Wilck <mwilck@suse.com>

---

 libmultipath/structs.c | 82 +++++++++++++++---------------------------

 1 file changed, 29 insertions(+), 53 deletions(-)

diff --git a/libmultipath/structs.c b/libmultipath/structs.c

index 9f86eb69..471087e2 100644

--- a/libmultipath/structs.c

+++ b/libmultipath/structs.c

@@ -6,6 +6,7 @@

 #include <unistd.h>

 #include <libdevmapper.h>

 #include <libudev.h>

+#include <ctype.h>

 #include "checkers.h"

 #include "memory.h"

@@ -633,7 +634,7 @@ int add_feature(char **f, const char *n)

 int remove_feature(char **f, const char *o)

 {

-	int c = 0, d, l;

+	int c = 0, d;

 	char *e, *p, *n;

 	const char *q;

@@ -644,33 +645,35 @@ int remove_feature(char **f, const char *o)

 	if (!o || *o == '\0')

 		return 0;

-	/* Check if not present */

-	if (!strstr(*f, o))

+	d = strlen(o);

+	if (isspace(*o) || isspace(*(o + d - 1))) {

+		condlog(0, "internal error: feature \"%s\" has leading or trailing spaces", o);

+		return 1;

+	}

+

+	/* Check if present and not part of a larger feature token*/

+	p = *f + 1; /* the size must be at the start of the features string */

+	while ((p = strstr(p, o)) != NULL) {

+		if (isspace(*(p - 1)) &&

+		    (isspace(*(p + d)) || *(p + d) == '\0'))

+			break;

+		p += d;

+	}

+	if (!p)

 		return 0;

 	/* Get feature count */

 	c = strtoul(*f, &e, 10);

-	if (*f == e)

-		/* parse error */

+	if (*f == e || !isspace(*e)) {

+		condlog(0, "parse error in feature string \"%s\"", *f);

 		return 1;

-

-	/* Normalize features */

-	while (*o == ' ') {

-		o++;

 	}

-	/* Just spaces, return */

-	if (*o == '\0')

-		return 0;

-	q = o + strlen(o);

-	while (*q == ' ')

-		q--;

-	d = (int)(q - o);

 	/* Update feature count */

 	c--;

 	q = o;

-	while (q[0] != '\0') {

-		if (q[0] == ' ' && q[1] != ' ' && q[1] != '\0')

+	while (*q != '\0') {

+		if (isspace(*q) && !isspace(*(q + 1)) && *(q + 1) != '\0')

 			c--;

 		q++;

 	}

@@ -684,15 +687,8 @@ int remove_feature(char **f, const char *o)

 		goto out;

 	}

-	/* Search feature to be removed */

-	e = strstr(*f, o);

-	if (!e)

-		/* Not found, return */

-		return 0;

-

 	/* Update feature count space */

-	l = strlen(*f) - d;

-	n =  MALLOC(l + 1);

+	n =  MALLOC(strlen(*f) - d + 1);

 	if (!n)

 		return 1;

@@ -702,36 +698,16 @@ int remove_feature(char **f, const char *o)

 	 * Copy existing features up to the feature

 	 * about to be removed

 	 */

-	p = strchr(*f, ' ');

-	if (!p) {

-		/* Internal error, feature string inconsistent */

-		FREE(n);

-		return 1;

-	}

-	while (*p == ' ')

-		p++;

-	p--;

-	if (e != p) {

-		do {

-			e--;

-			d++;

-		} while (*e == ' ');

-		e++; d--;

-		strncat(n, p, (size_t)(e - p));

-		p += (size_t)(e - p);

-	}

+	strncat(n, e, (size_t)(p - e));

 	/* Skip feature to be removed */

 	p += d;

-

 	/* Copy remaining features */

-	if (strlen(p)) {

-		while (*p == ' ')

-			p++;

-		if (strlen(p)) {

-			p--;

-			strcat(n, p);

-		}

-	}

+	while (isspace(*p))

+		p++;

+	if (*p != '\0')

+		strcat(n, p);

+	else

+		strchop(n);

 out:

 	FREE(*f);