[Bug 2006739] Re: Please enable Memory Tagging Extension in Ubuntu glibc

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: glibc (Ubuntu)
       Status: New => Confirmed

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Title:
  Please enable Memory Tagging Extension in Ubuntu glibc

Status in glibc package in Ubuntu:
  Confirmed

Bug description:
  Hello,
  For Debian Bookworm, Memory Tagging Extension (MTE) support is enabled in glibc:
  https://sources.debian.org/src/glibc/2.35-3/debian/sysdeps/arm64.mk/

  Would it be possible to please do a similar thing for the Ubuntu
  package?

  For more information, please see:
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995269

  ===

  glibc 2.33 onwards has support for 'Memory Tagging Extension' on
  arm64. Could you please enable this feature (by setting
  --enable-memory-tagging in the config).

  The effect is to add colouring bits into heap pointers so that typical
  illegal accesses (either temporally or spatially) can be detected and
  faulted. Glibc just has the userspace heap tagging - there is also
  corresponding kernel support.

  The functionality operates on arm ISA 8.5 or later, which has extra
  instructions to manipulate the tag bits in pointers.

  The details are explained in
  https://developer.arm.com/-/media/Arm%20Developer%20Community/PDF/Arm_Memory_Tagging_Extension_Whitepaper.pdf

  The implementation has been designed so that it is safe to enable in
  distros (which makes a change!). ifunc and HWCAP are used to link
  MTE-ready versions of relevant functions on hardware supporting
  ARMv8.5 instruction set or later. On eailer hardware things will work
  just as they do now.

  Here is the (trivial) patch:
  diff -u debian/sysdeps/arm64.mk~ debian/sysdeps/arm64.mk
  --- debian/sysdeps/arm64.mk~	2021-08-24 14:31:06.000000000 +0000
  +++ debian/sysdeps/arm64.mk	2021-09-28 19:43:58.782118977 +0000
  @@ -1,2 +1,2 @@
   # configuration options for all flavours
  -extra_config_options = --enable-multi-arch --enable-static-pie
  +extra_config_options = --enable-multi-arch --enable-static-pie --enable-memory-tagging

  
  --
  Wookey

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