generic-library/bionic
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix segv when unwinding stack past __libc_init.

Browse Source 
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
This commit is contained in:
Evgeniy Stepanov 2012-04-10 14:10:11 +04:00
parent 8c4f3ce8d0
commit cd15bacf33
1 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
libc/arch-arm/bionic/crtbegin_dynamic.S
View File

@ -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__