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Fix run-time warnings in sanitized builds (-fsanitize=undefined,address,alignment)

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The patch fixes three family of warnings:

dynasm/dasm_x86.h:146:46: runtime error: applying non-zero offset 18446744073642442752 to null pointer

dynasm/dasm_x86.h:193:32: runtime error: signed integer overflow: 2147483647 + 128 cannot be represented in type 'int'

dynasm/dasm_x86.h:446:23: runtime error: store to misaligned address 0x7fd86dd5e013 ...

line numbers in the error messages may be not accurate.
This commit is contained in:
Dmitry Stogov 2023-12-26 21:43:22 +03:00
parent c525bcb902
commit f54baaf0c6
1 changed files with 24 additions and 11 deletions
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35
dynasm/dasm_x86.h
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@ -79,6 +79,9 @@ struct dasm_State {
/* The size of the core structure depends on the max. number of sections. */
#define DASM_PSZ(ms) (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
/* Perform potentially overflowing pointer operations in a way that avoids UB. */
#define DASM_PTR_SUB(p1, off) ((void *) ((uintptr_t) (p1) - sizeof(*p1) * (uintptr_t) (off)))
#define DASM_PTR_ADD(p1, off) ((void *) ((uintptr_t) (p1) + sizeof(*p1) * (uintptr_t) (off)))
/* Initialize DynASM state. */
void dasm_init(Dst_DECL, int maxsection)
@ -140,7 +143,7 @@ void dasm_setup(Dst_DECL, const void *actionlist)
if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
for (i = 0; i < D->maxsection; i++) {
D->sections[i].pos = DASM_SEC2POS(i);
D->sections[i].rbuf = D->sections[i].buf - D->sections[i].pos;
D->sections[i].rbuf = DASM_PTR_SUB(D->sections[i].buf, D->sections[i].pos);
D->sections[i].ofs = 0;
}
}
@ -190,12 +193,12 @@ void dasm_put(Dst_DECL, int start, ...)
case DASM_DISP:
if (n == 0) { if (mrm < 0) mrm = p[-2]; if ((mrm&7) != 5) break; }
/* fallthrough */
case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
case DASM_IMM_DB: if ((((unsigned)n+128)&-256) == 0) goto ob; /* fallthrough */
case DASM_REL_A: /* Assumes ptrdiff_t is int. !x64 */
case DASM_IMM_D: ofs += 4; break;
case DASM_IMM_S: CK(((n+128)&-256) == 0, RANGE_I); goto ob;
case DASM_IMM_S: CK((((unsigned)n+128)&-256) == 0, RANGE_I); goto ob;
case DASM_IMM_B: CK((n&-256) == 0, RANGE_I); ob: ofs++; break;
case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
case DASM_IMM_WB: if ((((unsigned)n+128)&-256) == 0) goto ob; /* fallthrough */
case DASM_IMM_W: CK((n&-65536) == 0, RANGE_I); ofs += 2; break;
case DASM_SPACE: p++; ofs += n; break;
case DASM_SETLABEL: b[pos-2] = -0x40000000; break; /* Neg. label ofs. */
@ -359,12 +362,22 @@ int dasm_link(Dst_DECL, size_t *szp)
#define dasmb(x) *cp++ = (unsigned char)(x)
#ifndef DASM_ALIGNED_WRITES
# if defined(__has_attribute) && __has_attribute(__aligned__)
# define DASM_UNALIGNED(decl) decl __attribute__((__aligned__(1)))
# elif defined(_WIN32)
# define DASM_UNALIGNED(decl) __declspec(align(1)) decl
# else
# define DASM_UNALIGNED(decl) decl
# endif
typedef DASM_UNALIGNED(unsigned short unaligned_short);
typedef DASM_UNALIGNED(unsigned int unaligned_int);
typedef DASM_UNALIGNED(unsigned long long unaligned_long_long);
#define dasmw(x) \
do { *((unsigned short *)cp) = (unsigned short)(x); cp+=2; } while (0)
do { *((unaligned_short *)cp) = (unsigned short)(x); cp+=2; } while (0)
#define dasmd(x) \
do { *((unsigned int *)cp) = (unsigned int)(x); cp+=4; } while (0)
do { *((unaligned_int *)cp) = (unsigned int)(x); cp+=4; } while (0)
#define dasmq(x) \
do { *((unsigned long long *)cp) = (unsigned long long)(x); cp+=8; } while (0)
do { *((unaligned_long_long *)cp) = (unsigned long long)(x); cp+=8; } while (0)
#else
#define dasmw(x) do { dasmb(x); dasmb((x)>>8); } while (0)
#define dasmd(x) do { dasmw(x); dasmw((x)>>16); } while (0)
@ -392,7 +405,7 @@ int dasm_encode(Dst_DECL, void *buffer)
for (secnum = 0; secnum < D->maxsection; secnum++) {
dasm_Section *sec = D->sections + secnum;
int *b = sec->buf;
int *endb = sec->rbuf + sec->pos;
int *endb = DASM_PTR_ADD(sec->rbuf, sec->pos);
while (b != endb) {
dasm_ActList p = D->actionlist + *b++;
@ -406,16 +419,16 @@ int dasm_encode(Dst_DECL, void *buffer)
if (*p != DASM_IMM_DB && *p != DASM_IMM_WB) mark = NULL;
if (n == 0) { int mrm = mm[-1]&7; if (mrm == 4) mrm = mm[0]&7;
if (mrm != 5) { mm[-1] -= 0x80; break; } }
if (((n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40;
if ((((unsigned)n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40;
}
/* fallthrough */
case DASM_IMM_S: case DASM_IMM_B: wb: dasmb(n); break;
case DASM_IMM_DB: if (((n+128)&-256) == 0) {
case DASM_IMM_DB: if ((((unsigned)n+128)&-256) == 0) {
db: if (!mark) mark = cp; mark[-2] += 2; mark = NULL; goto wb;
} else mark = NULL;
/* fallthrough */
case DASM_IMM_D: wd: dasmd(n); break;
case DASM_IMM_WB: if (((n+128)&-256) == 0) goto db; else mark = NULL;
case DASM_IMM_WB: if ((((unsigned)n+128)&-256) == 0) goto db; else mark = NULL;
/* fallthrough */
case DASM_IMM_W: dasmw(n); break;
case DASM_VREG: {