[FFe] late glibc upload due to CVE-2024-2961

[Simon Chopin]

A new CVE for glibc was just published: CVE-2024-2961

We obviously want that fixed in Noble, and the upstream patch has already been backported to the relevant branch. On that branch are several patchsets that I was already planning on incorporating as part of any future glibc SRU to noble, so I'd like to do a "full" upload of glibc rather than the minimalistic cherry-pick one.

Here is the annotated changelog of what I'd like to upload:

glibc (2.39-0ubuntu9) noble; urgency=medium

  [ Matthias Klose ]
  * Define _DISTRO_EVADE_TIME_BITS for the build, not setting _TIME_BITS
    and _FILE_OFFSET_BITS in the compiler by default.
    See https://sourceware.org/bugzilla/show_bug.cgi?id=31624.
-> build fix, mostly useful for c-t-b(-p)

  [ Simon Chopin ]
  * debian/patches/git-updates.diff: update from upstream stable branch:
    - Fix support for -mtls-dialect=gnu2 on x86 and armhf:
      7fc8242bf8 x86-64: Save APX registers in ld.so trampoline
      a364304718 x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers
      853e915fdd x86-64: Update _dl_tlsdesc_dynamic to preserve AMX registers
      354cabcb26 x86-64: Allocate state buffer space for RDI, RSI and RBX
      15aebdbada Ignore undefined symbols for -mtls-dialect=gnu2
      a8ba52bde5 arm: Update _dl_tlsdesc_dynamic to preserve caller-saved registers (BZ 31372)
      aded2fc004 elf: Enable TLS descriptor tests on aarch64
      5a461f2949 Add tst-gnu2-tls2mod1 to test-internal-extras
-> Only touches codepaths that are touched by code using -mtls-dialect=gnu2, which is not the default. Low priority, but still worthwhile to fix.

    - Fix performance regression on AMD Zen3+ architecture (LP: #2030515):
      aa4249266e x86: Fix Zen3/Zen4 ERMS selection (BZ 30994)
      6484a92698 x86: Do not prefer ERMS for memset on Zen3+
      5d070d12b3 x86: Expand the comment on when REP STOSB is used on memset
-> Rather dramatic performance regression, that and the SVE one were my main motivation for an SRU.

    - 31c7d69af5 i386: Use generic memrchr in libc (bug 31316)
-> That one is pretty irrelevant for us.

    - b0e0a07018 aarch64/fpu: Sync libmvec routines from 2.39 and before with AOR
-> "fix for big-endian in AdvSIMD log, some cosmetic changes, and numerous small optimisations". Not SRU material, I admit.

    - Work around issues with SVE support in kernel (related to LP 1999551)
      395a89f61e aarch64: fix check for SVE support in assembler
      9d92452c70 AArch64: Check kernel version for SVE ifuncs
-> This SVE kernel regression was actually discovered when testing our SRU in bug 1999551 !

    - Build fixes for amd64v3:
      9883f4304c x86-64: Don't use SSE resolvers for ISA level 3 or above
      7b92f46f04 x86-64: Simplify minimum ISA check ifdef conditional with if
-> Nice to have for our amd64v3 experiments.
    - edb9a76e30 powerpc: Fix ld.so address determination for PCREL mode (bug 31640)
-> Straight fix

    - 04df8652eb Apply the Makefile sorting fix
-> Purely cosmetic

    - amd64v3 fix:
      423099a032 x86_64: Exclude SSE, AVX and FMA4 variants in libm multiarch
-> Again, nice to have.

    - 31da30f23c iconv: ISO-2022-CN-EXT: fix out-of-bound writes when writing escape sequence (CVE-2024-2961)
      (LP: #2062228)
-> The reason for this late upload!!

  * Revert the frame pointer changes on ppc64el.
    It doesn't really make sense on that architecture, and causes a
    performance regression on some workloads.

[Graham Inggs (ginggs)]

This is bugfixes only, I don't believe an exception is required, so please go ahead.