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| author |   Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> | 2020-02-04 14:06:42 -0800 |
|---|---|---|
| committer |   GitHub <noreply@github.com> | 2020-02-04 14:06:42 -0800 |
| commit | c352e6c7446c894b13643f538db312092b351789 (patch) | |
| tree | d924f8c3d763b216e83c1db39874a0de133a107b | |
| parent | [3.6] bpo-39401: Avoid unsafe DLL load on Windows 7 and earlier (GH-18231) (G... (diff) | |
| download | cpython-c352e6c7446c894b13643f538db312092b351789.tar.gz cpython-c352e6c7446c894b13643f538db312092b351789.tar.bz2 cpython-c352e6c7446c894b13643f538db312092b351789.zip | |
closes bpo-39510: Fix use-after-free in BufferedReader.readinto() (GH-18350)
When called on a closed object, readinto() segfaults on account
of a write to a freed buffer:
==220553== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==220553== Access not within mapped region at address 0x2A
==220553== at 0x48408A0: memmove (vg_replace_strmem.c:1272)
==220553== by 0x58DB0C: _buffered_readinto_generic (bufferedio.c:972)
==220553== by 0x58DCBA: _io__Buffered_readinto_impl (bufferedio.c:1053)
==220553== by 0x58DCBA: _io__Buffered_readinto (bufferedio.c.h:253)
Reproducer:
reader = open ("/dev/zero", "rb")
_void = reader.read (42)
reader.close ()
reader.readinto (bytearray (42)) GH-GH-GH- BANG!
The problem exists since 2012 when commit dc469454ec added code
to free the read buffer on close().
Signed-off-by: Philipp Gesang <philipp.gesang@intra2net.com>
(cherry picked from commit cb1c0746f277052e45a60d6c436a765e34722821)
Co-authored-by: Philipp Gesang <phg@phi-gamma.net>
Co-authored-by: Philipp Gesang <phg@phi-gamma.net>
| -rw-r--r-- | Lib/test/test_io.py | 5 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2020-02-04-10-27-41.bpo-39510.PMIh-f.rst | 1 | ||||
| -rw-r--r-- | Modules/_io/bufferedio.c | 1 |
3 files changed, 7 insertions, 0 deletions
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index f29c16cb47c..4ba46563b99 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -707,6 +707,11 @@ class IOTest(unittest.TestCase): file.seek(0) file.close() self.assertRaises(ValueError, file.read) + with self.open(support.TESTFN, "rb") as f: + file = self.open(f.fileno(), "rb", closefd=False) + self.assertEqual(file.read()[:3], b"egg") + file.close() + self.assertRaises(ValueError, file.readinto, bytearray(1)) def test_no_closefd_with_filename(self): # can't use closefd in combination with a file name diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-02-04-10-27-41.bpo-39510.PMIh-f.rst b/Misc/NEWS.d/next/Core and Builtins/2020-02-04-10-27-41.bpo-39510.PMIh-f.rst new file mode 100644 index 00000000000..9a38e4ab762 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-02-04-10-27-41.bpo-39510.PMIh-f.rst @@ -0,0 +1 @@ +Fix segfault in ``readinto()`` method on closed BufferedReader. diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c index 32355813e88..3e463098881 100644 --- a/Modules/_io/bufferedio.c +++ b/Modules/_io/bufferedio.c @@ -993,6 +993,7 @@ _buffered_readinto_generic(buffered *self, Py_buffer *buffer, char readinto1) PyObject *res = NULL; CHECK_INITIALIZED(self) + CHECK_CLOSED(self, "readinto of closed file") n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t); if (n > 0) { |