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| author | Florian Weimer <fweimer@redhat.com> | 2021-02-25 12:10:57 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2021-02-25 12:13:02 +0100 |
| commit | 035c012e32c11e84d64905efaf55e74f704d3668 (patch) | |
| tree | 7b08a9e9cbd8e4dd2e420cd6b7c204aeb5d61ccc /sysdeps/ia64 | |
| parent | a79328c745219dcb395070cdcd3be065a8347f24 (diff) | |
| download | glibc-035c012e32c11e84d64905efaf55e74f704d3668.tar.gz glibc-035c012e32c11e84d64905efaf55e74f704d3668.tar.xz glibc-035c012e32c11e84d64905efaf55e74f704d3668.zip | |
Reduce the statically linked startup code [BZ #23323]
It turns out the startup code in csu/elf-init.c has a perfect pair of ROP gadgets (see Marco-Gisbert and Ripoll-Ripoll, "return-to-csu: A New Method to Bypass 64-bit Linux ASLR"). These functions are not needed in dynamically-linked binaries because DT_INIT/DT_INIT_ARRAY are already processed by the dynamic linker. However, the dynamic linker skipped the main program for some reason. For maximum backwards compatibility, this is not changed, and instead, the main map is consulted from __libc_start_main if the init function argument is a NULL pointer. For statically linked binaries, the old approach based on linker symbols is still used because there is nothing else available. A new symbol version __libc_start_main@@GLIBC_2.34 is introduced because new binaries running on an old libc would not run their ELF constructors, leading to difficult-to-debug issues.
Diffstat (limited to 'sysdeps/ia64')
| -rw-r--r-- | sysdeps/ia64/dl-lookupcfg.h | 2 | ||||
| -rw-r--r-- | sysdeps/ia64/start.S | 9 |
2 files changed, 3 insertions, 8 deletions
diff --git a/sysdeps/ia64/dl-lookupcfg.h b/sysdeps/ia64/dl-lookupcfg.h index 209d926bad..58ca32424b 100644 --- a/sysdeps/ia64/dl-lookupcfg.h +++ b/sysdeps/ia64/dl-lookupcfg.h @@ -50,7 +50,7 @@ extern void attribute_hidden _dl_unmap (struct link_map *map); { \ ElfW(Addr) addr; \ DL_DT_FUNCTION_ADDRESS(map, start, , addr) \ - init_t init = (init_t) addr; \ + dl_init_t init = (dl_init_t) addr; \ init (argc, argv, env); \ } diff --git a/sysdeps/ia64/start.S b/sysdeps/ia64/start.S index 0018acc821..b28f8cb429 100644 --- a/sysdeps/ia64/start.S +++ b/sysdeps/ia64/start.S @@ -82,20 +82,15 @@ _start: { addl r11 = @ltoff(__libc_ia64_register_backing_store_base), gp addl out0 = @ltoff(@fptr(main)), gp - addl out3 = @ltoff(@fptr(__libc_csu_init)), gp + mov out3 = r0 /* Used to be init. */ ;; } { .mmi ld8 r3 = [r11] /* pointer to __libc_ia64_register_backing_store_base */ ld8 out0 = [out0] /* pointer to `main' function descriptor */ - addl out4 = @ltoff(@fptr(__libc_csu_fini)), gp + mov out4 = r0 /* Used to be fini. */ ;; } - { .mmi - ld8 out3 = [out3] /* pointer to `init' function descriptor */ - ld8 out4 = [out4] /* pointer to `fini' function descriptor */ - nop 0 - } .body { .mib st8 [r3] = r10 |