Re: [PATCH setup 00/14] Use libsolv, solve all our problems... (WIP)

[Ken Brown <kbrown@cornell.edu>]

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On 10/10/2017 7:18 AM, Ken Brown wrote:
> On 9/29/2017 4:33 PM, Ken Brown wrote:
>> I'll resume my testing after I return.
> 
> I've just started testing (based on the current HEAD of topic/libsolv), 
> and so far everything looks good.

I came across a situation where a SolvableVersion method was being 
called on a trivial object (with pool and id both 0).  This caused a 
crash when pool_id2solvable(pool, id) was called and pool was 
dereferenced.  There's probably a bug that led to this situation.  [It 
involved a local install in which a package was listed in two different 
setup.ini files, but the tarballs existed only in one.]  I plan to 
investigate this further.  But in any case, we shouldn't crash.  Patch 
attached.

Ken

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From f3b3c60ed473a1ef4e5b1ae5fcd1bfc46a6210fb Mon Sep 17 00:00:00 2001
From: Ken Brown <kbrown@cornell.edu>
Date: Tue, 17 Oct 2017 08:12:48 -0400
Subject: [PATCH] Avoid dereferencing NULL pointers

The libsolv function pool_id2solvable unconditionally dereferences its
first argument ('pool').  Callers must check that this argument is
non-NULL to avoid crashes.
---
 libsolv.cc | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/libsolv.cc b/libsolv.cc
index 78e73a8..3a244d4 100644
--- a/libsolv.cc
+++ b/libsolv.cc
@@ -75,6 +75,8 @@ RelId2Operator(Id id)
 const std::string
 SolvableVersion::Name () const
 {
+  if (!pool)
+    return "";
   Solvable *solvable = pool_id2solvable(pool, id);
   return std::string(pool_id2str(pool, solvable->name));
 }
@@ -82,6 +84,8 @@ SolvableVersion::Name () const
 const std::string
 SolvableVersion::Canonical_version() const
 {
+  if (!pool)
+    return "";
   Solvable *solvable = pool_id2solvable(pool, id);
   return std::string(pool_id2str(pool, solvable->evr));
 }
@@ -89,6 +93,8 @@ SolvableVersion::Canonical_version() const
 package_type_t
 SolvableVersion::Type () const
 {
+  if (!pool)
+    return package_binary;
   Solvable *solvable = pool_id2solvable(pool, id);
   if (solvable->arch == ARCH_SRC)
     return package_source;
@@ -112,6 +118,9 @@ SolvableVersion::obsoletes() const
 const PackageDepends
 SolvableVersion::deplist(Id keyname) const
 {
+  static PackageDepends empty_package;
+  if (!pool)
+    return empty_package;
   Solvable *solvable = pool_id2solvable(pool, id);
 
   Queue q;
@@ -147,13 +156,14 @@ SolvableVersion::deplist(Id keyname) const
     }
 
   // otherwise, return an empty depends list
-  static PackageDepends empty_package;
   return empty_package;
 }
 
 const std::string
 SolvableVersion::SDesc () const
 {
+  if (!pool)
+    return "";
   Solvable *solvable = pool_id2solvable(pool, id);
   const char *sdesc = repo_lookup_str(solvable->repo, id, SOLVABLE_SUMMARY);
   return sdesc;
@@ -197,6 +207,8 @@ SolvableVersion::sourcePackage () const
 void
 SolvableVersion::fixup_spkg_id (SolvableVersion spkg_id) const
 {
+  if (!pool)
+    return;
   Solvable *solvable = pool_id2solvable(pool, id);
   Repodata *data = repo_last_repodata(solvable->repo);
   Id handle = id;
@@ -237,6 +249,8 @@ SolvableVersion::accessible () const
 package_stability_t
 SolvableVersion::Stability () const
 {
+  if (!pool)
+    return TRUST_UNKNOWN;
   Solvable *solvable = pool_id2solvable(pool, id);
   Id stability_attr = pool_str2id(pool, "solvable:stability", 1);
   return (package_stability_t)repo_lookup_num(solvable->repo, id, stability_attr, TRUST_UNKNOWN);
-- 
2.14.2