Bug #12292
closedRace between OpenSSL::SSL::SSLSocket#stop and #connect can cause a segmentation fault
Description
The following code will demonstrate the issue:
require "openssl"
require "socket"
ctx = OpenSSL::SSL::SSLContext.new
ctx.ciphers = "aNULL"
sock1, sock2 = UNIXSocket.pair
ssl1 = OpenSSL::SSL::SSLSocket.new(sock1, ctx)
ssl2 = OpenSSL::SSL::SSLSocket.new(sock2, ctx)
t = Thread.new { ssl1.connect } # => segmentation fault
ssl2.accept
ssl1.close # calls #stop (private method)
sock1.close
t.value
The SSL (OpenSSL land object) can be freed by SSLSocket#stop (#close) while SSLSocket#connect is still using it. This happens because SSLSocket#connect releases GVL while waiting for the peer.
There are two ways to resolve this:
- Check that the SSL object is still set every time after reacquiring GVL
- Change SSLSocket#stop not to free the SSL object
The latter introduces an incompatibility (#stop is currently documented as "prepares it for another connection").
I however prefer this because similar bugs can be introduced in future if we choose an ad-hoc way, and I don't think anyone reuses the SSLSocket object (keep in mind that we don't have interface to replace the underlying IO object).
Anyway I attach fixes in both way.
- 0001-ext-openssl-check-that-the-SSL-object-is-still-set-a.patch: the fix in the first way
- 0001-ext-openssl-make-OpenSSL-SSL-SSLSocket-non-reusable.patch: the fix in the second way
- 0002-ext-openssl-some-trivial-cleanups.patch: some minor cleanups, not actually related to this issue (what's the most desirable way to submit such trivial patches?)
Files
Updated by shyouhei (Shyouhei Urabe) over 8 years ago
- Status changed from Open to Assigned
- Assignee set to rhenium (Kazuki Yamaguchi)
Kazuki, I think it's OK for you to fix a segmentation fault now.
Updated by Anonymous over 8 years ago
- Status changed from Assigned to Closed
Applied in changeset r55100.
openssl: fix possible SEGV on race between SSLSocket#stop and #connect
-
ext/openssl/ossl_ssl.c (ossl_ssl_stop): Don't free the SSL struct
here. Since some methods such as SSLSocket#connect releases GVL,
there is a chance of use after free if we free the SSL from another
thread. SSLSocket#stop was documented as "prepares it for another
connection" so this is a slightly incompatible change. However when
this sentence was added (r30090, Add toplevel documentation for
OpenSSL, 2010-12-06), it didn't actually. The current behavior is
from r40304 (Correct shutdown behavior w.r.t GC., 2013-04-15).
[ruby-core:74978] [Bug #12292] -
ext/openssl/lib/openssl/ssl.rb (sysclose): Update doc.
-
test/openssl/test_ssl.rb: Test this.
Updated by usa (Usaku NAKAMURA) over 8 years ago
- Backport changed from 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN to 2.1: WONTFIX, 2.2: REQUIRED, 2.3: REQUIRED
Updated by nagachika (Tomoyuki Chikanaga) about 8 years ago
- Backport changed from 2.1: WONTFIX, 2.2: REQUIRED, 2.3: REQUIRED to 2.1: WONTFIX, 2.2: REQUIRED, 2.3: DONE
ruby_2_3 r55866 merged revision(s) 55100.
Updated by rhenium (Kazuki Yamaguchi) about 8 years ago
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