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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-01-03 09:56:28 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-02-03 10:58:23 -0300 |
| commit | d5aaece8a3528ff5f9cc0ceeb067da0e47436669 (patch) | |
| tree | ebc3ef75eec7d9e6483b563837ab9cb68e60bb38 /NEWS | |
| parent | 56e00c585420af63fc4df9e28ff9e12bb2a3274f (diff) | |
| download | glibc-d5aaece8a3528ff5f9cc0ceeb067da0e47436669.tar.gz glibc-d5aaece8a3528ff5f9cc0ceeb067da0e47436669.tar.xz glibc-d5aaece8a3528ff5f9cc0ceeb067da0e47436669.zip | |
elf: Fix GL(dl_phdr) and GL(dl_phnum) for static builds [BZ #29864]
The 73fc4e28b9464f0e refactor did not add the GL(dl_phdr) and
GL(dl_phnum) for static build, relying on the __ehdr_start symbol,
which is always added by the static linker, to get the correct values.
This is problematic in some ways:
- The segment may see its in-memory size differ from its in-file
size (or the binary may have holes). The Linux has fixed is to
provide concise values for both AT_PHDR and AT_PHNUM (commit
0da1d5002745c - "fs/binfmt_elf: Fix AT_PHDR for unusual ELF files")
- Some archs (alpha for instance) the hidden weak reference is not
correctly pulled by the static linker and __ehdr_start address
end up being 0, which makes GL(dl_phdr) and GL(dl_phnum) have both
invalid values (and triggering a segfault later on libc.so while
accessing TLS variables).
The safer fix is to just restore the previous behavior to setup
GL(dl_phdr) and GL(dl_phnum) for static based on kernel auxv. The
__ehdr_start fallback can also be simplified by not assuming weak
linkage (as for PIE).
The libc-static.c auxv init logic is moved to dl-support.c, since
the later is build without SHARED and then GLRO macro is defined
to access the variables directly.
The _dl_phdr is also assumed to be always non NULL, since an invalid
NULL values does not trigger TLS initialization (which is used in
various libc systems).
Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
(cherry picked from commit 7e31d166510ac4adbf53d5e8144c709a37dd8c7a)
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/NEWS b/NEWS index 8c79e83b77..c5e142eb3a 100644 --- a/NEWS +++ b/NEWS @@ -26,6 +26,8 @@ The following bugs are resolved with this release: [12154] Do not fail DNS resolution for CNAMEs which are not host names [24816] Fix tst-nss-files-hosts-long on single-stack hosts [28846] CMSG_NXTHDR may trigger -Wstrict-overflow warning + [29864] libc: __libc_start_main() should obtain program headers + address (_dl_phdr) from the auxv, not the ELF header. [29305] Conserve NSS buffer space during DNS packet parsing [29402] nscd: nscd: No such file or directory [29415] nscd: Fix netlink cache invalidation if epoll is used |