From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Tue, 20 May 2025 09:57:39 +0000 (+0200)
Subject: [3.14] gh-131505: Move len boundary assertions before using len. (GH-131536) (GH... 
X-Git-Tag: v3.14.0b2~104
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ccaf865364692087dc74252dd411f6356a1d43f0;p=thirdparty%2FPython%2Fcpython.git

[3.14] gh-131505: Move len boundary assertions before using len. (GH-131536) (GH-134239)

gh-131505: Move len boundary assertions before using len. (GH-131536)

Move len boundary assertions before using len.
(cherry picked from commit c45e661226558e997e265cf53ce1419213cc10b7)

Co-authored-by: naya451 <41294408+naya451@users.noreply.github.com>
---

diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index e45a2d1a16dc..8bc7aeacf294 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -583,9 +583,9 @@ _io_BytesIO_readinto_impl(bytesio *self, Py_buffer *buffer)
             len = 0;
     }
 
-    memcpy(buffer->buf, PyBytes_AS_STRING(self->buf) + self->pos, len);
     assert(self->pos + len < PY_SSIZE_T_MAX);
     assert(len >= 0);
+    memcpy(buffer->buf, PyBytes_AS_STRING(self->buf) + self->pos, len);
     self->pos += len;
 
     return PyLong_FromSsize_t(len);