From: akr@fsij.org
To: ruby-core@ruby-lang.org
Subject: [ruby-core:69672] [Ruby trunk - Bug #11270] Coverity Scan warns out-of-bounds access in ext/socket
Date: Fri, 19 Jun 2015 01:36:47 +0000 [thread overview]
Message-ID: <redmine.journal-53032.20150619013646.3141f20db984fad7@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-11270.20150616182142@ruby-lang.org
Issue #11270 has been updated by Akira Tanaka.
Yusuke Endoh wrote:
> Honestly I'm not sure the C language specification: is it guaranteed that a pointer to a field of a union and a pointer to the union itself? In short, `(void*)&arg.buf.addr == (void*)&arg.buf`? If it is guaranteed, there is no problem. But I couldn't find the guarantee from the specification.
Yes.
There is a description in the committee draft of C99.
```
[#13] The size of a union is sufficient to contain the
largest of its members. The value of at most one of the
members can be stored in a union object at any time. A
pointer to a union object, suitably converted, points to
each of its members (or if a member is a bit-field, then to
the unit in which it resides), and vice versa.
```
This section is quoted to Wikipedia (from C90).
https://en.wikipedia.org/wiki/Union_type
JIS X 3010:2003 section 6.7.2.1 has same description in Japanese.
> I'm not familiar with socket apis. Do you mean that the apis are ill-designed so that we cannot use them in the strict C language? If so, I agree that it is difficult to fix.
I don't say "cannot" here.
----------------------------------------
Bug #11270: Coverity Scan warns out-of-bounds access in ext/socket
https://bugs.ruby-lang.org/issues/11270#change-53032
* Author: Yusuke Endoh
* Status: Open
* Priority: Normal
* Assignee:
* ruby -v:
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
Hello,
Coverity Scan warns ext/socket/init.c and raddrinfo.c.
`rsock_s_recvfrom` in ext/socket/init.c does:
arg.alen = (socklen_t)sizeof(arg.buf);
then calls `rsock_io_socket_addrinfo`:
return rb_assoc_new(str, rsock_io_socket_addrinfo(sock, &arg.buf.addr, arg.alen));
`rsock_io_socket_addrinfo` indirectly calls `init_addrinfo` in ext/socket/raddrinfo.c.
(`rsock_io_socket_addrinfo` -> `rsock_fd_socket_addrinfo` -> `rsock_addrinfo_new` -> `init_addrinfo`)
`init_addrinfo` does:
memcpy((void *)&rai->addr, (void *)sa, len);
Note that `sa` is `&arg.buf.addr`, and `len` is `arg.alen`. `&arg.buf.addr` is a pointer to sockaddr, and `arg.len` is `sizeof(union_sockaddr)`, not `sizeof(sockaddr)`, which is indeed inconsistent.
I don't think this inconsistency will cause actual harm, but it would be better to fix.
--
Yusuke Endoh <mame@ruby-lang.org>
--
https://bugs.ruby-lang.org/
next prev parent reply other threads:[~2015-06-19 1:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-11270.20150616182142@ruby-lang.org>
2015-06-16 18:21 ` [ruby-core:69613] [Ruby trunk - Bug #11270] [Open] Coverity Scan warns out-of-bounds access in ext/socket mame
2015-06-18 7:49 ` [ruby-core:69647] [Ruby trunk - Bug #11270] [Feedback] " akr
2015-06-18 15:59 ` [ruby-core:69662] [Ruby trunk - Bug #11270] [Open] " mame
2015-06-19 1:36 ` akr [this message]
2015-06-19 14:11 ` [ruby-core:69681] [Ruby trunk - Bug #11270] [Rejected] " mame
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