Howdy,
Marc Mutz, a colleague of mine, is stumbling over ubsan reporting
misaligned stores in sljit code (when used from QRegularExpression).
You can see some of the discussion going on here:
https://codereview.qt-project.org/#/c/165159/
I'm attaching his patch (against PCRE SVN HEAD), which makes "make
check" succeed in a ubsan build of PCRE. Without the patch, it
otherwise fails with http://pastebin.com/UagaK2As . The patch needs to
be slightly reworked anyhow because the compiler emits some conversion
warnings (see the above link).
Any feedback is kindly appreciated :)
Cheers,
--
Giuseppe D'Angelo
Index: sljit/sljitConfigInternal.h
===================================================================
--- sljit/sljitConfigInternal.h (revision 1661)
+++ sljit/sljitConfigInternal.h (working copy)
@@ -214,6 +214,10 @@
#define SLJIT_MEMMOVE(dest, src, len) memmove(dest, src, len)
#endif
+#ifndef SLJIT_MEMCPY
+#define SLJIT_MEMCPY(dest, src, len) memcpy(dest, src, len)
+#endif
+
#ifndef SLJIT_ZEROMEM
#define SLJIT_ZEROMEM(dest, len) memset(dest, 0, len)
#endif
@@ -409,6 +413,16 @@
#endif /* !SLJIT_W */
+/******************************************************/
+/* Unaligned-store functions */
+/******************************************************/
+
+static SLJIT_INLINE void sljit_unaligned_store_s32(void *addr, sljit_s32 value)
+{ SLJIT_MEMCPY(addr, &value, sizeof(value)); }
+
+static SLJIT_INLINE void sljit_unaligned_store_sw(void *addr, sljit_sw value)
+{ SLJIT_MEMCPY(addr, &value, sizeof(value)); }
+
/*************************/
/* Endianness detection. */
/*************************/
Index: sljit/sljitNativeX86_64.c
===================================================================
--- sljit/sljitNativeX86_64.c (revision 1661)
+++ sljit/sljitNativeX86_64.c (working copy)
@@ -35,7 +35,7 @@
INC_SIZE(2 + sizeof(sljit_sw));
*inst++ = REX_W | ((reg_map[reg] <= 7) ? 0 : REX_B);
*inst++ = MOV_r_i32 + (reg_map[reg] & 0x7);
- *(sljit_sw*)inst = imm;
+ sljit_unaligned_store_sw(inst, imm);
return SLJIT_SUCCESS;
}
@@ -219,7 +219,7 @@
*inst++ = REX_W;
*inst++ = GROUP_BINARY_81;
*inst++ = MOD_REG | SUB | 4;
- *(sljit_s32*)inst = local_size;
+ sljit_unaligned_store_s32(inst, local_size);
inst += sizeof(sljit_s32);
}
@@ -292,7 +292,7 @@
*inst++ = REX_W;
*inst++ = GROUP_BINARY_81;
*inst++ = MOD_REG | ADD | 4;
- *(sljit_s32*)inst = compiler->local_size;
+ sljit_unaligned_store_s32(inst, compiler->local_size);
}
tmp = compiler->scratches;
@@ -339,7 +339,7 @@
if (rex)
*inst++ = rex;
*inst++ = opcode;
- *(sljit_s32*)inst = imm;
+ sljit_unaligned_store_s32(inst, imm);
return SLJIT_SUCCESS;
}
@@ -354,6 +354,7 @@
sljit_u8 rex = 0;
sljit_s32 flags = size & ~0xf;
sljit_s32 inst_size;
+ sljit_s32 tmp_s32;
/* The immediate operand must be 32 bit. */
SLJIT_ASSERT(!(a & SLJIT_IMM) || compiler->mode32 || IS_HALFWORD(imma));
@@ -516,7 +517,7 @@
if (immb <= 127 && immb >= -128)
*buf_ptr++ = immb; /* 8 bit
displacement. */
else {
- *(sljit_s32*)buf_ptr = immb; /* 32 bit
displacement. */
+ sljit_unaligned_store_s32(buf_ptr,
immb); /* 32 bit displacement. */
buf_ptr += sizeof(sljit_s32);
}
}
@@ -543,7 +544,7 @@
else if (flags & EX86_HALF_ARG)
*(short*)buf_ptr = imma;
else if (!(flags & EX86_SHIFT_INS))
- *(sljit_s32*)buf_ptr = imma;
+ sljit_unaligned_store_s32(buf_ptr, imma);
}
return !(flags & EX86_SHIFT_INS) ? inst : (inst + 1);
Index: sljit/sljitNativeX86_common.c
===================================================================
--- sljit/sljitNativeX86_common.c (revision 1661)
+++ sljit/sljitNativeX86_common.c (working copy)
@@ -534,7 +534,7 @@
*(sljit_sw*)jump->addr =
(sljit_sw)(jump->u.label->addr - (jump->addr + sizeof(sljit_sw)));
#else
SLJIT_ASSERT((sljit_sw)(jump->u.label->addr -
(jump->addr + sizeof(sljit_s32))) >= HALFWORD_MIN &&
(sljit_sw)(jump->u.label->addr - (jump->addr + sizeof(sljit_s32))) <=
HALFWORD_MAX);
- *(sljit_s32*)jump->addr =
(sljit_s32)(jump->u.label->addr - (jump->addr + sizeof(sljit_s32)));
+ sljit_unaligned_store_s32(jump->addr,
(sljit_s32)(jump->u.label->addr - (jump->addr + sizeof(sljit_s32))));
#endif
}
else {
@@ -542,7 +542,7 @@
*(sljit_sw*)jump->addr =
(sljit_sw)(jump->u.target - (jump->addr + sizeof(sljit_sw)));
#else
SLJIT_ASSERT((sljit_sw)(jump->u.target -
(jump->addr + sizeof(sljit_s32))) >= HALFWORD_MIN && (sljit_sw)(jump->u.target
- (jump->addr + sizeof(sljit_s32))) <= HALFWORD_MAX);
- *(sljit_s32*)jump->addr =
(sljit_s32)(jump->u.target - (jump->addr + sizeof(sljit_s32)));
+ sljit_unaligned_store_s32(jump->addr,
(sljit_s32)(jump->u.target - (jump->addr + sizeof(sljit_s32))));
#endif
}
}
--
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