From 3d1333293ef48117060cd4e285e9c49a6d061e83 Mon Sep 17 00:00:00 2001

From: Karel Zak <kzak@redhat.com>

Date: Tue, 15 Dec 2015 12:25:56 +0100

Subject: [PATCH 63/84] login, mount: fix __SC_GETPW_R_SIZE_MAX usage

sysconf(_SC_GETPW_R_SIZE_MAX) returns initial suggested size for pwd

buffer (see getpwnam_r man page or POSIX). This is not large enough in

some cases.

Yes, this sysconf option is misnamed (should be _SC_GETPW_R_SIZE_MIN).

Upstream: http://github.com/karelzak/util-linux/commit/f7ac9e71b18fa7314151f2ab65ee0bdd2ea89c07

Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1290689

Signed-off-by: Karel Zak <kzak@redhat.com>

---

 include/c.h          |  7 +++++++

 libmount/src/utils.c | 25 ++++++-------------------

 login-utils/login.c  | 12 ++----------

 3 files changed, 15 insertions(+), 29 deletions(-)

diff --git a/include/c.h b/include/c.h

index a50e8a5..7b59ce8 100644

--- a/include/c.h

+++ b/include/c.h

@@ -300,4 +300,11 @@ static inline int usleep(useconds_t usec)

 # define SEEK_HOLE	4

 #endif

+/*

+ * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for

+ * pwd buffer and in some cases it is not large enough. See POSIX and

+ * getpwnam_r man page for more details.

+ */

+#define UL_GETPW_BUFSIZ	(16 * 1024)

+

 #endif /* UTIL_LINUX_C_H */

diff --git a/libmount/src/utils.c b/libmount/src/utils.c

index 9305bb8..7c6f5b1 100644

--- a/libmount/src/utils.c

+++ b/libmount/src/utils.c

@@ -538,16 +538,6 @@ int mnt_get_filesystems(char ***filesystems, const char *pattern)

 	return rc;

 }

-static size_t get_pw_record_size(void)

-{

-#ifdef _SC_GETPW_R_SIZE_MAX

-	long sz = sysconf(_SC_GETPW_R_SIZE_MAX);

-	if (sz > 0)

-		return sz;

-#endif

-	return 16384;

-}

-

 /*

  * Returns allocated string with username or NULL.

  */

@@ -555,14 +545,13 @@ char *mnt_get_username(const uid_t uid)

 {

         struct passwd pwd;

 	struct passwd *res;

-	size_t sz = get_pw_record_size();

 	char *buf, *username = NULL;

-	buf = malloc(sz);

+	buf = malloc(UL_GETPW_BUFSIZ);

 	if (!buf)

 		return NULL;

-	if (!getpwuid_r(uid, &pwd, buf, sz, &res) && res)

+	if (!getpwuid_r(uid, &pwd, buf, UL_GETPW_BUFSIZ, &res) && res)

 		username = strdup(pwd.pw_name);

 	free(buf);

@@ -574,17 +563,16 @@ int mnt_get_uid(const char *username, uid_t *uid)

 	int rc = -1;

         struct passwd pwd;

 	struct passwd *pw;

-	size_t sz = get_pw_record_size();

 	char *buf;

 	if (!username || !uid)

 		return -EINVAL;

-	buf = malloc(sz);

+	buf = malloc(UL_GETPW_BUFSIZ);

 	if (!buf)

 		return -ENOMEM;

-	if (!getpwnam_r(username, &pwd, buf, sz, &pw) && pw) {

+	if (!getpwnam_r(username, &pwd, buf, UL_GETPW_BUFSIZ, &pw) && pw) {

 		*uid= pw->pw_uid;

 		rc = 0;

 	} else {

@@ -602,17 +590,16 @@ int mnt_get_gid(const char *groupname, gid_t *gid)

 	int rc = -1;

         struct group grp;

 	struct group *gr;

-	size_t sz = get_pw_record_size();

 	char *buf;

 	if (!groupname || !gid)

 		return -EINVAL;

-	buf = malloc(sz);

+	buf = malloc(UL_GETPW_BUFSIZ);

 	if (!buf)

 		return -ENOMEM;

-	if (!getgrnam_r(groupname, &grp, buf, sz, &gr) && gr) {

+	if (!getgrnam_r(groupname, &grp, buf, UL_GETPW_BUFSIZ, &gr) && gr) {

 		*gid= gr->gr_gid;

 		rc = 0;

 	} else {

diff --git a/login-utils/login.c b/login-utils/login.c

index a59dd3a..e0e960f 100644

--- a/login-utils/login.c

+++ b/login-utils/login.c

@@ -671,22 +671,14 @@ static struct passwd *get_passwd_entry(const char *username,

 					 struct passwd *pwd)

 {

 	struct passwd *res = NULL;

-	size_t sz = 16384;

 	int x;

 	if (!pwdbuf || !username)

 		return NULL;

-#ifdef _SC_GETPW_R_SIZE_MAX

-	{

-		long xsz = sysconf(_SC_GETPW_R_SIZE_MAX);

-		if (xsz > 0)

-			sz = (size_t) xsz;

-	}

-#endif

-	*pwdbuf = xrealloc(*pwdbuf, sz);

+	*pwdbuf = xrealloc(*pwdbuf, UL_GETPW_BUFSIZ);

-	x = getpwnam_r(username, pwd, *pwdbuf, sz, &res;;

+	x = getpwnam_r(username, pwd, *pwdbuf, UL_GETPW_BUFSIZ, &res;;

 	if (!res) {

 		errno = x;

 		return NULL;

-- 

2.7.4