BZ#14498: fix infinite loop in nss_db_getservbyname

BZ#14498: fix infinite loop in nss_db_getservbyname

[Alexandre Oliva]

nss_db uses nss_files code for services, but a continue on protocol
mismatch that doesn't affect nss_files skipped the code that advanced
to the next db entry.  Any one of these changes would suffice to fix
it, but fixing both makes them both safer to reuse elsewhere.

Regression tested on x86_64-linux-gnu.  Ok to install?


for  ChangeLog

	[BZ #14498]
	* NEWS: Fixed.
	* nss/nss_db/db-XXX.c (_nss_db_get##name##_r): Update hidx
	after parsing line but before break_if_match.
	* nss/nss_files/files-service (DB_LOOKUP): Don't "continue;"
	if there is a protocol mismatch.
---
 NEWS                          |    8 ++++----
 nss/nss_db/db-XXX.c           |    9 ++++++---
 nss/nss_files/files-service.c |    7 +++++--
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/NEWS b/NEWS
index 918b4a1..9ed697c 100644
--- a/NEWS
+++ b/NEWS
@@ -9,10 +9,10 @@ Version 2.21
 
 * The following bugs are resolved with this release:
 
-  6652, 12926, 14132, 14138, 14171, 15215, 15884, 17266, 17344, 17363,
-  17370, 17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508, 17522,
-  17555, 17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584, 17585,
-  17589.
+  6652, 12926, 14132, 14138, 14171, 14498, 15215, 15884, 17266, 17344,
+  17363, 17370, 17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508,
+  17522, 17555, 17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584,
+  17585, 17589.
 
 * New locales: tu_IN, bh_IN.
 \f
diff --git a/nss/nss_db/db-XXX.c b/nss/nss_db/db-XXX.c
index 89b1a12..e950887 100644
--- a/nss/nss_db/db-XXX.c
+++ b/nss/nss_db/db-XXX.c
@@ -191,6 +191,12 @@ enum nss_status								      \
       char *p = memcpy (buffer, valstr, len);				      \
 									      \
       int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS);      \
+									      \
+      /* Advance before break_if_match, lest it uses continue to skip
+	 to the next entry.  */						      \
+      if ((hidx += hval2) >= header->dbs[i].hashsize)			      \
+	hidx -= header->dbs[i].hashsize;				      \
+									      \
       if (err > 0)							      \
 	{								      \
 	  status = NSS_STATUS_SUCCESS;					      \
@@ -203,9 +209,6 @@ enum nss_status								      \
 	  status = NSS_STATUS_TRYAGAIN;					      \
 	  break;							      \
 	}								      \
-									      \
-      if ((hidx += hval2) >= header->dbs[i].hashsize)			      \
-	hidx -= header->dbs[i].hashsize;				      \
     }									      \
 									      \
   if (status == NSS_STATUS_NOTFOUND)					      \
diff --git a/nss/nss_files/files-service.c b/nss/nss_files/files-service.c
index 2401cb0..c28c62f 100644
--- a/nss/nss_files/files-service.c
+++ b/nss/nss_files/files-service.c
@@ -44,8 +44,11 @@ DB_LOOKUP (servbyname, ':',
 	   {
 	     /* Must match both protocol (if specified) and name.  */
 	     if (proto != NULL && strcmp (result->s_proto, proto))
-	       continue;
-	     LOOKUP_NAME (s_name, s_aliases)
+	       /* A continue statement here breaks nss_db, because it
+		bypasses advancing to the next db entry, and it
+		doesn't make nss_files any more efficient.  */;
+	     else
+	       LOOKUP_NAME (s_name, s_aliases)
 	   },
 	   const char *name, const char *proto)
 


-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer

Re: BZ#14498: fix infinite loop in nss_db_getservbyname

[Siddhesh Poyarekar]

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On Thu, Nov 13, 2014 at 07:52:29PM -0200, Alexandre Oliva wrote:
> nss_db uses nss_files code for services, but a continue on protocol
> mismatch that doesn't affect nss_files skipped the code that advanced
> to the next db entry.  Any one of these changes would suffice to fix
> it, but fixing both makes them both safer to reuse elsewhere.
> 
> Regression tested on x86_64-linux-gnu.  Ok to install?
> 
> 
> for  ChangeLog
> 
> 	[BZ #14498]
> 	* NEWS: Fixed.
> 	* nss/nss_db/db-XXX.c (_nss_db_get##name##_r): Update hidx
> 	after parsing line but before break_if_match.
> 	* nss/nss_files/files-service (DB_LOOKUP): Don't "continue;"
> 	if there is a protocol mismatch.

Looks good to me.

Thanks,
Siddhesh

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