youknowone · Aug 29, 2026 · Aug 28, 2026 · Aug 28, 2026 · Aug 28, 2026 · Aug 28, 2026
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
@@ -258,6 +258,32 @@ def copyfileobj(src, dst, length=None, exception=OSError, bufsize=None):
         dst.write(buf)
     return
 
+# Maximum number of bytes read in a single call when reading a member's
+# extended header (a GNU long name/link or a pax header).  The size of such
+# a header is taken from the archive and is not trustworthy, so it is read in
+# bounded chunks to avoid a huge up-front allocation when a crafted or
+# truncated archive claims far more data than the file actually contains
+# (gh-151497).
+_EXTHEADER_READ_CHUNK = 1024 * 1024  # 1 MiB
+
+def _safe_read(fileobj, size):
+    """Read up to *size* bytes from *fileobj* in bounded chunks.
+
+    Returns the same bytes as ``fileobj.read(size)`` would (including a short
+    result at end of file), but limits pre-allocation, so an
+    oversized size field in a crafted header cannot force a huge allocation.
+    """
+    if size <= _EXTHEADER_READ_CHUNK:
+        return fileobj.read(size)
+    chunks = []
+    while size > 0:
+        chunk = fileobj.read(min(size, _EXTHEADER_READ_CHUNK))
+        if not chunk:
+            break
+        chunks.append(chunk)
+        size -= len(chunk)
+    return b"".join(chunks)
+
 def _safe_print(s):
     encoding = getattr(sys.stdout, 'encoding', None)
     if encoding is not None:
@@ -524,7 +550,9 @@ def seek(self, pos=0):
         if pos - self.pos >= 0:
             blocks, remainder = divmod(pos - self.pos, self.bufsize)
             for i in range(blocks):
-                self.read(self.bufsize)
+                data = self.read(self.bufsize)
+                if not data:
+                    break
             self.read(remainder)
         else:
             raise StreamError("seeking backwards is not allowed")
@@ -1429,7 +1457,7 @@ def _proc_gnulong(self, tarfile):
         """Process the blocks that hold a GNU longname
            or longlink member.
         """
-        buf = tarfile.fileobj.read(self._block(self.size))
+        buf = _safe_read(tarfile.fileobj, self._block(self.size))
 
         # Fetch the next header and process it.
         try:
@@ -1485,7 +1513,7 @@ def _proc_pax(self, tarfile):
            POSIX.1-2008.
         """
         # Read the header information.
-        buf = tarfile.fileobj.read(self._block(self.size))
+        buf = _safe_read(tarfile.fileobj, self._block(self.size))
 
         # A pax header stores supplemental information for either
         # the following file (extended) or all following files
@@ -2510,7 +2538,8 @@ def extract(self, member, path="", set_attrs=True, *, numeric_owner=False,
         tarinfo, unfiltered = self._get_extract_tarinfo(
             member, filter_function, path)
         if tarinfo is not None:
-            self._extract_one(tarinfo, path, set_attrs, numeric_owner)
+            self._extract_one(tarinfo, path, set_attrs, numeric_owner,
+                              filter_function=filter_function)
 
     def _get_extract_tarinfo(self, member, filter_function, path):
         """Get (filtered, unfiltered) TarInfos from *member*
@@ -2782,6 +2811,9 @@ def makelink_with_filter(self, tarinfo, targetpath,
                     "makelink_with_filter: if filter_function is not None, "
                     + "extraction_root must also not be None")
             try:
+                filter_function(
+                    unfiltered.replace(name=tarinfo.name, deep=False),
+                    extraction_root)
                 filtered = filter_function(unfiltered, extraction_root)
             except _FILTER_ERRORS as cause:
                 raise LinkFallbackError(tarinfo, unfiltered.name) from cause

diff --git a/Lib/tempfile.py b/Lib/tempfile.py
@@ -915,7 +915,8 @@ def __init__(self, suffix=None, prefix=None, dir=None,
     @classmethod
     def _rmtree(cls, name, ignore_errors=False, repeated=False):
         def onexc(func, path, exc):
-            if isinstance(exc, PermissionError):
+            # On DragonFly BSD, UF_NOUNLINK removal fails with EISDIR, not EPERM.
+            if isinstance(exc, (PermissionError, IsADirectoryError)):
                 if repeated and path == name:
                     if ignore_errors:
                         return