[Bug 2076419] Re: lxml: Does not respect compiler flags

[Julian Andres Klode]

lxml is ready IMO

** Changed in: lxml (Ubuntu Noble)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/2076419

Title:
  lxml: Does not respect compiler flags

Status in lxml package in Ubuntu:
  Fix Committed
Status in lxml source package in Noble:
  In Progress

Bug description:
  [Impact]
  The packaging does not respect compiler flags, notably hardening flags like the stack protector, as well as frame pointer, as it never uses dpkg-buildflags and is still old manual style.

  This means there is a higher security risk, which given the nature of
  the library seems ill-advised, and the lack of frame pointers hampers
  profiling.

  [Test plan]
  Skim at the build log and see that the build flags have been passed, notably stuff like

  -fno-strict-overflow
  -Werror=implicit-function-declaration
  -fno-omit-frame-pointer
  -mno-omit-leaf-frame-pointer
  -fstack-protector-strong
  -fstack-clash-protection
  -Wformat
  -Werror=for

  Run https://gist.github.com/julian-
  klode/85e55553f85c410a1b856a93dce77208 on the ELF binaries and ensure
  that all lines have -fno-omit-frame-pointer

  Run a smoke test to see the parser still works:

  from lxml import etree
  from urllib.request import urlopen

  with urlopen("https://www.w3.org/TR/REC-xml/REC-xml-20081126.xml") as xml:
      xml=xml.read()
  tree=etree.fromstring(xml, base_url="https://www.w3.org/TR/REC-xml/REC-xml-20081126.xml")

  for element in tree.iter():
      print(element)

  print(etree.tostring(tree))

  [Where problems could occur]
  Hardening flags could surface existing (possibly security) bugs that have been asymptomatic so far; frame pointers will incur some slow down.

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