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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2018-08-27 16:16:43 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2018-09-25 16:27:50 -0300 |
| commit | b5c45e83753b27dc538dff2d55d4410c385cf3a4 (patch) | |
| tree | 7c88e09f3bcf2edbdf2a1196b50c54ab7459b0c5 /config.make.in | |
| parent | d62f9ec0cce26a275ec68f4564814041a33395b1 (diff) | |
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Fix ifunc support with DT_TEXTREL segments (BZ#20480)
Currently, DT_TEXTREL is incompatible with IFUNC. When DT_TEXTREL or
DF_TEXTREL is seen, the dynamic linker calls __mprotect on the segments
with PROT_READ|PROT_WRITE before applying dynamic relocations. It leads
to segfault when performing IFUNC resolution (which requires PROT_EXEC
as well for the IFUNC resolver).
This patch makes it call __mprotect with extra PROT_WRITE bit, which
will keep the PROT_EXEC bit if exists, and thus fixes the segfault.
FreeBSD rtld libexec/rtld-elf/rtld.c (reloc_textrel_prot) does the same.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
sparc64-linux-gnu, sparcv9-linux-gnu, and armv8-linux-gnueabihf.
Adam J. Richte <adam_richter2004@yahoo.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Fangrui Song <maskray@google.com>
[BZ #20480]
* config.h.in (CAN_TEXTREL_IFUNC): New define.
* configure.ac: Add check if linker supports textrel relocation with
ifunc.
* elf/dl-reloc.c (_dl_relocate_object): Use all required flags on
DT_TEXTREL segments, not only PROT_READ and PROT_WRITE.
* elf/Makefile (ifunc-pie-tests): Add tst-ifunc-textrel.
(CFLAGS-tst-ifunc-textrel.c): New rule.
* elf/tst-ifunc-textrel.c: New file.
Diffstat (limited to 'config.make.in')
| -rw-r--r-- | config.make.in | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/config.make.in b/config.make.in index a6fe48d31f..f46bfc29bb 100644 --- a/config.make.in +++ b/config.make.in @@ -75,6 +75,7 @@ use-default-link = @use_default_link@ output-format = @libc_cv_output_format@ have-cxx-thread_local = @libc_cv_cxx_thread_local@ have-loop-to-function = @libc_cv_cc_loop_to_function@ +have-textrel_ifunc = @libc_cv_textrel_ifunc@ multi-arch = @multi_arch@ |