Bug #55978: rgw_lua_request.cc warning: the address of ‘rgw::IAM::Policy::statements’ will never be NULL - rgw - Ceph

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Bug #55978

closed

rgw_lua_request.cc warning: the address of ‘rgw::IAM::Policy::statements’ will never be NULL

Added by Casey Bodley almost 2 years ago. Updated almost 2 years ago.

Status:

Resolved

Priority:

Normal

Assignee:

Yuval Lifshitz

Target version:

% Done:

Source:

Tags:

Backport:

Regression:

Severity:

3 - minor

Reviewed:

Affected Versions:

ceph-qa-suite:

Pull request ID:

46617

Crash signature (v1):

Crash signature (v2):

Description

[297/358] Building CXX object src/rgw/CMakeFiles/rgw_a.dir/rgw_lua_request.cc.o
src/rgw/rgw_lua_request.cc: In static member function ‘static int rgw::lua::request::PolicyMetaTable::IndexClosure(lua_State*)’:
src/rgw/rgw_lua_request.cc:497:48: warning: the address of ‘rgw::IAM::Policy::statements’ will never be NULL [-Waddress]
  497 |       create_metatable<StatementsMetaTable>(L, &(policy->statements));
      |                                                ^~~~~~~~~~~~~~~~~~~~~
In file included from src/rgw/rgw_common.h:29,
                 from src/rgw/rgw_service.h:14,
                 from src/rgw/services/svc_zone.h:6,
                 from src/rgw/rgw_lua_request.cc:5:
src/rgw/rgw_iam_policy.h:511:26: note: ‘rgw::IAM::Policy::statements’ declared here
  511 |   std::vector<Statement> statements;
      |                          ^~~~~~~~~~

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Updated by Yuval Lifshitz almost 2 years ago

this warning is strange, since the code does not check for NULL or nullptr on that pointer.
maybe this is because the upvalues (this pointer is one of them) are used as a template parameter pack?

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Updated by Casey Bodley almost 2 years ago

i see two overloads of this function in rgw_lua_utils.h:

template<typename MetaTable, typename... Upvalues>
void create_metatable(lua_State* L, bool toplevel, Upvalues... upvalues)

template<typename MetaTable>
void create_metatable(lua_State* L, bool toplevel, std::unique_ptr<typename MetaTable::Type>& ptr)

it looks like this warning is complaining that we're passing &(policy->statements) as bool toplevel, which (because it never evaluates to NULL) would always evaluate to toplevel = true

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Updated by Yuval Lifshitz almost 2 years ago

ok. in this case it is a bug. the value of "top-level" should just be "false" (since this is not a top-level field).
the pointer should be passed as the first upvalue

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