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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/microblaze | |
| parent | a79328c745219dcb395070cdcd3be065a8347f24 (diff) | |
| download | glibc-035c012e32c11e84d64905efaf55e74f704d3668.tar.gz | |
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/microblaze')
| -rw-r--r-- | sysdeps/microblaze/start.S | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/sysdeps/microblaze/start.S b/sysdeps/microblaze/start.S index dcb202a63b..6589bd4dc7 100644 --- a/sysdeps/microblaze/start.S +++ b/sysdeps/microblaze/start.S @@ -63,14 +63,14 @@ _start: mfs r20,rpc addik r20,r20,_GLOBAL_OFFSET_TABLE_+8 lwi r5,r20,main@GOT - lwi r8,r20,__libc_csu_init@GOT - lwi r9,r20,__libc_csu_fini@GOT + addk r8,r0,r0 /* Used to be init. */ + addk r9,r0,r0 /* Used to be fini. */ brid __libc_start_main@PLT addk r10,r0,r0 #else addik r5,r0,main - addik r8,r0,__libc_csu_init - addik r9,r0,__libc_csu_fini + addk r8,r0,r0 /* Used to be init. */ + addk r9,r0,r0 /* Used to be fini. */ brid __libc_start_main addk r10,r0,r0 #endif |