commit 790b8dda4455865cb8c3a47801f4304c1a43baf6

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue May 19 14:09:38 2020 +0200

    nss_compat: internal_end*ent may clobber errno, hiding ERANGE [BZ #25976]

    During cleanup, before returning from get*_r functions, the end*ent

    calls must not change errno.  Otherwise, an ERANGE error from the

    underlying implementation can be hidden, causing unexpected lookup

    failures.  This commit introduces an internal_end*ent_noerror

    function which saves and restore errno, and marks the original

    internal_end*ent function as warn_unused_result, so that it is used

    only in contexts were errors from it can be handled explicitly.

    Reviewed-by: DJ Delorie <dj@redhat.com>

diff --git a/nss/nss_compat/compat-grp.c b/nss/nss_compat/compat-grp.c

index 012929eae7048702..fca9f4860f72e3d2 100644

--- a/nss/nss_compat/compat-grp.c

+++ b/nss/nss_compat/compat-grp.c

@@ -142,7 +142,7 @@ _nss_compat_setgrent (int stayopen)

 }

-static enum nss_status

+static enum nss_status __attribute_warn_unused_result__

 internal_endgrent (ent_t *ent)

 {

   if (ent->stream != NULL)

@@ -163,6 +163,15 @@ internal_endgrent (ent_t *ent)

   return NSS_STATUS_SUCCESS;

 }

+/* Like internal_endgrent, but preserve errno in all cases.  */

+static void

+internal_endgrent_noerror (ent_t *ent)

+{

+  int saved_errno = errno;

+  enum nss_status unused __attribute__ ((unused)) = internal_endgrent (ent);

+  __set_errno (saved_errno);

+}

+

 enum nss_status

 _nss_compat_endgrent (void)

 {

@@ -483,7 +492,7 @@ _nss_compat_getgrnam_r (const char *name, struct group *grp,

   if (result == NSS_STATUS_SUCCESS)

     result = internal_getgrnam_r (name, grp, &ent, buffer, buflen, errnop);

-  internal_endgrent (&ent;;

+  internal_endgrent_noerror (&ent;;

   return result;

 }

@@ -612,7 +621,7 @@ _nss_compat_getgrgid_r (gid_t gid, struct group *grp,

   if (result == NSS_STATUS_SUCCESS)

     result = internal_getgrgid_r (gid, grp, &ent, buffer, buflen, errnop);

-  internal_endgrent (&ent;;

+  internal_endgrent_noerror (&ent;;

   return result;

 }

diff --git a/nss/nss_compat/compat-initgroups.c b/nss/nss_compat/compat-initgroups.c

index 5beaa6b88b7e1764..d7a89ea8e7718ab0 100644

--- a/nss/nss_compat/compat-initgroups.c

+++ b/nss/nss_compat/compat-initgroups.c

@@ -133,7 +133,7 @@ internal_setgrent (ent_t *ent)

 }

-static enum nss_status

+static enum nss_status __attribute_warn_unused_result__

 internal_endgrent (ent_t *ent)

 {

   if (ent->stream != NULL)

@@ -157,6 +157,15 @@ internal_endgrent (ent_t *ent)

   return NSS_STATUS_SUCCESS;

 }

+/* Like internal_endgrent, but preserve errno in all cases.  */

+static void

+internal_endgrent_noerror (ent_t *ent)

+{

+  int saved_errno = errno;

+  enum nss_status unused __attribute__ ((unused)) = internal_endgrent (ent);

+  __set_errno (saved_errno);

+}

+

 /* Add new group record.  */

 static void

 add_group (long int *start, long int *size, gid_t **groupsp, long int limit,

@@ -501,7 +510,7 @@ _nss_compat_initgroups_dyn (const char *user, gid_t group, long int *start,

  done:

   scratch_buffer_free (&tmpbuf);

-  internal_endgrent (&intern;;

+  internal_endgrent_noerror (&intern;;

   return status;

 }

diff --git a/nss/nss_compat/compat-pwd.c b/nss/nss_compat/compat-pwd.c

index a903452cdf96de74..8832fb7518d8bbff 100644

--- a/nss/nss_compat/compat-pwd.c

+++ b/nss/nss_compat/compat-pwd.c

@@ -259,7 +259,7 @@ _nss_compat_setpwent (int stayopen)

 }

-static enum nss_status

+static enum nss_status __attribute_warn_unused_result__

 internal_endpwent (ent_t *ent)

 {

   if (ent->stream != NULL)

@@ -287,6 +287,15 @@ internal_endpwent (ent_t *ent)

   return NSS_STATUS_SUCCESS;

 }

+/* Like internal_endpwent, but preserve errno in all cases.  */

+static void

+internal_endpwent_noerror (ent_t *ent)

+{

+  int saved_errno = errno;

+  enum nss_status unused __attribute__ ((unused)) = internal_endpwent (ent);

+  __set_errno (saved_errno);

+}

+

 enum nss_status

 _nss_compat_endpwent (void)

 {

@@ -822,7 +831,7 @@ _nss_compat_getpwnam_r (const char *name, struct passwd *pwd,

   if (result == NSS_STATUS_SUCCESS)

     result = internal_getpwnam_r (name, pwd, &ent, buffer, buflen, errnop);

-  internal_endpwent (&ent;;

+  internal_endpwent_noerror (&ent;;

   return result;

 }

@@ -1061,7 +1070,7 @@ _nss_compat_getpwuid_r (uid_t uid, struct passwd *pwd,

   if (result == NSS_STATUS_SUCCESS)

     result = internal_getpwuid_r (uid, pwd, &ent, buffer, buflen, errnop);

-  internal_endpwent (&ent;;

+  internal_endpwent_noerror (&ent;;

   return result;

 }

diff --git a/nss/nss_compat/compat-spwd.c b/nss/nss_compat/compat-spwd.c

index eb96ca09172d5743..684a06007ab84ac9 100644

--- a/nss/nss_compat/compat-spwd.c

+++ b/nss/nss_compat/compat-spwd.c

@@ -215,7 +215,7 @@ _nss_compat_setspent (int stayopen)

 }

-static enum nss_status

+static enum nss_status __attribute_warn_unused_result__

 internal_endspent (ent_t *ent)

 {

   if (ent->stream != NULL)

@@ -244,6 +244,15 @@ internal_endspent (ent_t *ent)

   return NSS_STATUS_SUCCESS;

 }

+/* Like internal_endspent, but preserve errno in all cases.  */

+static void

+internal_endspent_noerror (ent_t *ent)

+{

+  int saved_errno = errno;

+  enum nss_status unused __attribute__ ((unused)) = internal_endspent (ent);

+  __set_errno (saved_errno);

+}

+

 enum nss_status

 _nss_compat_endspent (void)

 {

@@ -261,7 +270,6 @@ _nss_compat_endspent (void)

   return result;

 }

-

 static enum nss_status

 getspent_next_nss_netgr (const char *name, struct spwd *result, ent_t *ent,

 			 char *group, char *buffer, size_t buflen,

@@ -786,7 +794,7 @@ _nss_compat_getspnam_r (const char *name, struct spwd *pwd,

   if (result == NSS_STATUS_SUCCESS)

     result = internal_getspnam_r (name, pwd, &ent, buffer, buflen, errnop);

-  internal_endspent (&ent;;

+  internal_endspent_noerror (&ent;;

   return result;

 }