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android_bionic
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Expose a function to reset the stack protector for the zygote. 

This is already covered by the existing test by virtue of being used for
all threads.

Bug: http://b/168258494
Test: treehugger
Change-Id: I5c872fd7f30a4c79de1d70e7702f4b12d4e94cd3
This commit is contained in:
Elliott Hughes 2020-09-10 18:26:08 -07:00
parent bba9153c5c
commit a1e3f2c502
2 changed files with 15 additions and 5 deletions
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19
libc/bionic/__libc_init_main_thread.cpp
View File

@ -101,6 +101,19 @@ void __init_tcb_dtv(bionic_tcb* tcb) {
__set_tcb_dtv(tcb, const_cast<TlsDtv*>(&zero_dtv));
}
// This is public so that the zygote can call it too. It is not expected
// to be useful otherwise.
//
// Note in particular that it is not possible to return from any existing
// stack frame with stack protector enabled after this function is called.
extern "C" void android_reset_stack_guards() {
// The TLS stack guard is set from the global, so ensure that we've initialized the global
// before we initialize the TLS. Dynamic executables will initialize their copy of the global
// stack protector from the one in the main thread's TLS.
__libc_safe_arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard));
__init_tcb_stack_guard(__get_bionic_tcb());
}
// Finish initializing the main thread.
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
extern "C" void __libc_init_main_thread_late() {
@ -119,11 +132,7 @@ extern "C" void __libc_init_main_thread_late() {
// User code should never see this; we'll compute it when asked.
pthread_attr_setstacksize(&main_thread.attr, 0);
// The TLS stack guard is set from the global, so ensure that we've initialized the global
// before we initialize the TLS. Dynamic executables will initialize their copy of the global
// stack protector from the one in the main thread's TLS.
__libc_safe_arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard));
__init_tcb_stack_guard(__get_bionic_tcb());
android_reset_stack_guards();
__init_thread(&main_thread);

1
libc/libc.map.txt
View File

@ -1770,4 +1770,5 @@ LIBC_PLATFORM {
android_net_res_stats_get_info_for_net;
android_net_res_stats_aggregate;
android_net_res_stats_get_usable_servers;
android_reset_stack_guards;
} LIBC_Q;