[libvirt] [ruby-libvirt] Don't free more entries than we retrieved

Guido Günther agx at sigxcpu.org
Tue Jan 7 20:24:14 UTC 2014


The vir*List* functions return the number of fetched entries. We mustn't
free more, otherwise we'll crash like

 #0  0xb779d424 in __kernel_vsyscall ()
 #1  0xb733981f in __GI_raise (sig=sig at entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
 #2  0xb733ccd3 in __GI_abort () at abort.c:90
 #3  0xb7376275 in __libc_message (do_abort=do_abort at entry=2, fmt=fmt at entry=0xb74767d0 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:199
 #4  0xb7380e52 in malloc_printerr (action=<optimized out>, str=<optimized out>, ptr=0xb7087000) at malloc.c:4923
 #5  0xb7381b90 in _int_free (av=0xb74b7440 <main_arena>, p=0xb7086ff8, have_lock=0) at malloc.c:3779
 #6  0xb75c059f in ruby_xfree () from /usr/lib/libruby-1.9.1.so.1.9
 #7  0xb7076448 in ruby_libvirt_generate_list () from /usr/lib/ruby/vendor_ruby/1.9.1/i486-linux/_libvirt.so
...

since we're trying to free random addresses.
---
 ext/libvirt/connect.c    | 4 ++--
 ext/libvirt/domain.c     | 2 +-
 ext/libvirt/nodedevice.c | 2 +-
 ext/libvirt/storage.c    | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/ext/libvirt/connect.c b/ext/libvirt/connect.c
index 36cac20..1af64a1 100644
--- a/ext/libvirt/connect.c
+++ b/ext/libvirt/connect.c
@@ -67,7 +67,7 @@
         names = alloca(sizeof(char *) * num);                           \
         r = virConnectList##objs(ruby_libvirt_connect_get(c), names, num); \
         ruby_libvirt_raise_error_if(r < 0, e_RetrieveError, "virConnectList" # objs, ruby_libvirt_connect_get(c)); \
-        return ruby_libvirt_generate_list(num, names);                  \
+        return ruby_libvirt_generate_list(r < 0 ? 0 : r, names);        \
     } while(0)
 
 static VALUE c_connect;
@@ -1508,7 +1508,7 @@ static VALUE libvirt_connect_list_nodedevices(int argc, VALUE *argv, VALUE c)
     ruby_libvirt_raise_error_if(r < 0, e_RetrieveError, "virNodeListDevices",
                                 ruby_libvirt_connect_get(c));
 
-    return ruby_libvirt_generate_list(num, names);
+    return ruby_libvirt_generate_list(r < 0 ? 0 : r, names);
 }
 
 /*
diff --git a/ext/libvirt/domain.c b/ext/libvirt/domain.c
index ddce2d8..bc46753 100644
--- a/ext/libvirt/domain.c
+++ b/ext/libvirt/domain.c
@@ -1532,7 +1532,7 @@ static VALUE libvirt_domain_list_snapshots(int argc, VALUE *argv, VALUE d)
                                 "virDomainSnapshotListNames",
                                 ruby_libvirt_connect_get(d));
 
-    return ruby_libvirt_generate_list(num, names);
+    return ruby_libvirt_generate_list(r < 0 ? 0 : r, names);
 }
 
 /*
diff --git a/ext/libvirt/nodedevice.c b/ext/libvirt/nodedevice.c
index 98b3715..041cda2 100644
--- a/ext/libvirt/nodedevice.c
+++ b/ext/libvirt/nodedevice.c
@@ -124,7 +124,7 @@ static VALUE libvirt_nodedevice_list_caps(VALUE c)
                                 "virNodeDeviceListCaps",
                                 ruby_libvirt_connect_get(c));
 
-    return ruby_libvirt_generate_list(num, names);
+    return ruby_libvirt_generate_list(r < 0 ? 0 : r, names);
 }
 
 /*
diff --git a/ext/libvirt/storage.c b/ext/libvirt/storage.c
index 4b96d2e..008410a 100644
--- a/ext/libvirt/storage.c
+++ b/ext/libvirt/storage.c
@@ -340,7 +340,7 @@ static VALUE libvirt_storage_pool_list_volumes(VALUE p)
                                 "virStoragePoolListVolumes",
                                 ruby_libvirt_connect_get(p));
 
-    return ruby_libvirt_generate_list(num, names);
+    return ruby_libvirt_generate_list(r < 0 ? 0 : r, names);
 }
 
 /*
-- 
1.8.5.2




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