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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/m68k/start.S | |
| parent | a79328c745219dcb395070cdcd3be065a8347f24 (diff) | |
| download | glibc-035c012e32c11e84d64905efaf55e74f704d3668.zip glibc-035c012e32c11e84d64905efaf55e74f704d3668.tar.gz glibc-035c012e32c11e84d64905efaf55e74f704d3668.tar.bz2 | |
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/m68k/start.S')
| -rw-r--r-- | sysdeps/m68k/start.S | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/sysdeps/m68k/start.S b/sysdeps/m68k/start.S index c36b34f..98da4db 100644 --- a/sysdeps/m68k/start.S +++ b/sysdeps/m68k/start.S @@ -76,15 +76,14 @@ _start: pea (%a1) /* Push address of the shared library termination function. */ + /* These used to be addresses of the .fini and .init entry points. */ + clr.l -(%sp) + clr.l -(%sp) + #ifdef PIC /* Load PIC register. */ LOAD_GOT (%a5) - /* Push the address of our own entry points to `.fini' and - `.init'. */ - move.l __libc_csu_fini@GOT(%a5), -(%sp) - move.l __libc_csu_init@GOT(%a5), -(%sp) - pea (%a0) /* Push second argument: argv. */ move.l %d0, -(%sp) /* Push first argument: argc. */ @@ -94,10 +93,6 @@ _start: let the libc call main. */ jbsr __libc_start_main@PLTPC #else - /* Push the address of our own entry points to `.fini' and - `.init'. */ - pea __libc_csu_fini - pea __libc_csu_init pea (%a0) /* Push second argument: argv. */ move.l %d0, -(%sp) /* Push first argument: argc. */ |