For non-PIC, the stack protector patterns did:
rtx mem = XEXP (force_const_mem (SImode, operands[1]), 0);
emit_move_insn (operands[2], mem);
Here, operands[1] is the address of the canary (&__stack_chk_guard)
and operands[2] is the register that we want to move that address into.
However, the code above instead sets operands[2] to the address of a
constant pool entry that contains &__stack_chk_guard, rather than to
&__stack_chk_guard itself. The sequence therefore does one less
pointer indirection than it should.
The net effect was to use &__stack_chk_guard for stack-smash detection,
instead of using __stack_chk_guard itself.
Tested on arm-linux-gnueabi, arm-linux-gnueabihf and armeb-eabi.
OK for trunk and branches?
Richard
gcc/
* config/arm/arm.md (*stack_protect_combined_set_insn): For non-PIC,
load the address of the canary rather than the address of the
constant pool entry that points to it.
(*stack_protect_combined_test_insn): Likewise.
gcc/testsuite/
* gcc.target/arm/stack-protector-3.c: New test.
* gcc.target/arm/stack-protector-4.c: Likewise.
---
gcc/config/arm/arm.md | 4 +-
.../gcc.target/arm/stack-protector-3.c | 38 +++++++++++++++++++
.../gcc.target/arm/stack-protector-4.c | 6 +++
3 files changed, 46 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/arm/stack-protector-3.c
create mode 100644 gcc/testsuite/gcc.target/arm/stack-protector-4.c
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index bffdb0b3987..c4fa116ab77 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -9212,7 +9212,7 @@ (define_insn_and_split "*stack_protect_combined_set_insn"
operands[2] = operands[1];
else
{
- rtx mem = XEXP (force_const_mem (SImode, operands[1]), 0);
+ rtx mem = force_const_mem (SImode, operands[1]);
emit_move_insn (operands[2], mem);
}
}
@@ -9295,7 +9295,7 @@ (define_insn_and_split "*stack_protect_combined_test_insn"
operands[3] = operands[1];
else
{
- rtx mem = XEXP (force_const_mem (SImode, operands[1]), 0);
+ rtx mem = force_const_mem (SImode, operands[1]);
emit_move_insn (operands[3], mem);
}
}
diff --git a/gcc/testsuite/gcc.target/arm/stack-protector-3.c
b/gcc/testsuite/gcc.target/arm/stack-protector-3.c
new file mode 100644
index 00000000000..b8f77fa2309
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/stack-protector-3.c
@@ -0,0 +1,38 @@
+/* { dg-do run } */
+/* { dg-require-effective-target fstack_protector } */
+/* { dg-options "-fstack-protector-all -O2" } */
+
+extern volatile long *stack_chk_guard_ptr;
+
+void __attribute__ ((noipa))
+f (void)
+{
+ volatile int x;
+ /* Munging the contents of __stack_chk_guard should trigger a
+ stack-smashing failure for this function. */
+ *stack_chk_guard_ptr += 1;
+}
+
+asm (
+" .data\n"
+" .align 3\n"
+" .globl stack_chk_guard_ptr\n"
+"stack_chk_guard_ptr:\n"
+" .word __stack_chk_guard\n"
+" .weak __stack_chk_guard\n"
+"__stack_chk_guard:\n"
+" .word 0xdead4321\n"
+" .text\n"
+" .type __stack_chk_fail, %function\n"
+"__stack_chk_fail:\n"
+" movs r0, #0\n"
+" b exit\n"
+" .size __stack_chk_fail, .-__stack_chk_fail"
+);
+
+int
+main (void)
+{
+ f ();
+ __builtin_abort ();
+}
diff --git a/gcc/testsuite/gcc.target/arm/stack-protector-4.c
b/gcc/testsuite/gcc.target/arm/stack-protector-4.c
new file mode 100644
index 00000000000..6334dd00908
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/stack-protector-4.c
@@ -0,0 +1,6 @@
+/* { dg-do run } */
+/* { dg-require-effective-target fstack_protector } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-fstack-protector-all -O2 -fpic" } */
+
+#include "stack-protector-3.c"
