Add a checksum to jmp_buf on mips and mips64.
Make it easier to diagnose applications mucking with the contents of
jmp_buf by checksumming its contents.
Bug: http://b/27417786
Change-Id: I473bc2871dece23a9b9d02481945246160d671c6
diff --git a/libc/arch-mips/bionic/setjmp.S b/libc/arch-mips/bionic/setjmp.S
index 73002e8..3b4ff55 100644
--- a/libc/arch-mips/bionic/setjmp.S
+++ b/libc/arch-mips/bionic/setjmp.S
@@ -136,7 +136,7 @@
/* following fields are 8-byte aligned */
#define SC_FLAG_OFFSET (2*4) /* 8 bytes, cookie and savesigs flag, first actual field */
#define SC_MASK_OFFSET (4*4) /* 16 bytes, mips32/mips64 version of sigset_t */
-#define SC_SPARE_OFFSET (8*4) /* 8 bytes, reserved for future uses */
+#define SC_CKSUM_OFFSET (8*4) /* 8 bytes, used for checksum */
/* Registers that are 4-byte on mips32 o32, and 8-byte on mips64 n64 abi */
#define SC_REGS_OFFSET (10*4) /* SC_REGS_BYTES */
@@ -165,6 +165,8 @@
#error _JBLEN is too small
#endif
+#define USE_CHECKSUM 1
+
.macro m_mangle_reg_and_store reg, cookie, temp, offset
xor \temp, \reg, \cookie
REG_S \temp, \offset
@@ -175,6 +177,20 @@
xor \reg, \temp, \cookie
.endm
+.macro m_calculate_checksum dst, src, scratch
+ REG_L \dst, REGSZ(\src)
+#ifdef __LP64__
+ /* 64 bit: checksum offset is 4 (actual _JBLEN is 25) */
+ .irp i,2,3,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24
+#else
+ /* 32 bit: checksum offset is 8 (actual _JBLEN is 34) */
+ .irp i,2,3,4,5,6,7,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33
+#endif
+ REG_L \scratch, \i*REGSZ(\src)
+ xor \dst, \dst, \scratch
+ .endr
+.endm
+
/*
*
* GPOFF and FRAMESIZE must be the same for all setjmp/longjmp routines
@@ -263,6 +279,10 @@
s.d $f30, SC_FPREGS+5*REGSZ_FP(a0)
#endif
sw v0, SC_FPSR_OFFSET(a0)
+#if USE_CHECKSUM
+ m_calculate_checksum t0, a0, t1
+ REG_S t0, SC_CKSUM_OFFSET(a0)
+#endif
move v0, zero
RESTORE_GP64
PTR_ADDU sp, FRAMESZ
@@ -311,6 +331,16 @@
move s1, a1 # temp spill
move s0, a0
+#if USE_CHECKSUM
+ m_calculate_checksum t0, s0, s2
+ REG_L s2, SC_CKSUM_OFFSET(s0)
+ beq t0, s2, 0f
+ nop
+ jal __bionic_setjmp_checksum_mismatch
+ nop
+0:
+#endif
+
# extract savesigs flag
REG_L s2, SC_FLAG_OFFSET(s0)
andi t0, s2, 1
diff --git a/tests/setjmp_test.cpp b/tests/setjmp_test.cpp
index b7e856f..bb01601 100644
--- a/tests/setjmp_test.cpp
+++ b/tests/setjmp_test.cpp
@@ -254,7 +254,7 @@
if (value == 0) {
// Flip a bit.
- reinterpret_cast<long*>(jb)[0] ^= 1;
+ reinterpret_cast<long*>(jb)[1] ^= 1;
EXPECT_DEATH(longjmp(jb, 1), "checksum mismatch");
} else {
