From cd15bacf334ab254a5f61c3bba100adde1b6b80a Mon Sep 17 00:00:00 2001 From: Evgeniy Stepanov Date: Tue, 10 Apr 2012 14:10:11 +0400 Subject: Fix segv when unwinding stack past __libc_init. This change fixes a segmentation fault in the libc unwinder when it goes past __libc_init. Unwind instructions for __libc_init direct it to grab the return address from the stack frame. Without this change, the unwinder gets a wild address and looks up further unwind instructions for the routine at that address. If it's unlucky enough to hit an existing function, it will try to unwind it. Bad things happen then. With this change, the return address always points to the _start function, which does not have unwind instructions associated with it. This stop the unwind process. __libc_init never returns, so this does not affect program execution, other than adding 4 bytes on the main thread stack. Change-Id: Id58612172e8825c8729cccd081541a13bff96bd0 --- libc/arch-arm/bionic/crtbegin_dynamic.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'libc/arch-arm') diff --git a/libc/arch-arm/bionic/crtbegin_dynamic.S b/libc/arch-arm/bionic/crtbegin_dynamic.S index 6ca0845..ec6d482 100644 --- a/libc/arch-arm/bionic/crtbegin_dynamic.S +++ b/libc/arch-arm/bionic/crtbegin_dynamic.S @@ -53,7 +53,9 @@ _start: ldr r2, =main adr r3, 1f ldr r4, =__libc_init - bx r4 + blx r4 + mov r0, #0 + bx r0 1: .long __PREINIT_ARRAY__ .long __INIT_ARRAY__ -- cgit v1.1