Thanks Ingo for your extensive review! It contains lots of valuable
input for me.
I have applied all your recommendations, they make a lot of sense.
> I would suggest to use uint32_t.
Just while applying this, I noticed that the file has a mix of the
types u_int32_t and uint32_t. I took u_int32_t for now because it was
in there more often than uint32_t. What do you think?
> > +#ifndef __LP64__
> > + if (runetype_nranges > SIZE_MAX / sizeof(_RuneEntry) ||
> > + maplower_nranges > SIZE_MAX / sizeof(_RuneEntry) ||
> > + mapupper_nranges > SIZE_MAX / sizeof(_RuneEntry))
> > + return NULL;
> > +#endif
>
> I dislike using #ifdef, it seems error-prone to me. The checks
> are correct in any case. Sure, if size_t is much larger than uint32_t,
> these checks can never trigger. But why do micro-optimization here?
> Why not just delete the #ifndef/#endif?
If I skip this __LP64__ check, it triggers a gcc warning on amd64,
because the compiler tells me that the test is useless. So it's a
cosmetical thing. It's removed for now.
I still cast frl_variable_len to u_int32_t for ntohl, but will cast it
back to int32_t for a "less than 0" check. This should properly handle
error cases when it's been negative to begin with.
Tobias
Index: lib/libc/locale/rune.c
===================================================================
RCS file: /cvs/src/lib/libc/locale/rune.c,v
retrieving revision 1.4
diff -u -p -u -p -r1.4 rune.c
--- locale/rune.c 25 May 2014 17:47:04 -0000 1.4
+++ locale/rune.c 3 Dec 2015 21:55:54 -0000
@@ -59,32 +59,40 @@
* SUCH DAMAGE.
*/
+#include <sys/types.h>
+#include <sys/stat.h>
#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
#include <stdio.h>
-#include <string.h>
#include <stdlib.h>
-#include <errno.h>
+#include <string.h>
#include <wchar.h>
-#include <sys/types.h>
-#include <sys/stat.h>
#include "rune.h"
#include "rune_local.h"
-static int readrange(_RuneLocale *, _RuneRange *, _FileRuneRange *, void *,
FILE *);
+#define SAFE_ADD(x, y) \
+do { \
+ if ((x) > SIZE_MAX - (y)) \
+ return NULL; \
+ (x) += (y); \
+} while (0);
+
+static int readrange(_RuneLocale *, _RuneRange *, u_int32_t, void *, FILE *);
static void _freeentry(_RuneRange *);
static void _wctype_init(_RuneLocale *rl);
static int
-readrange(_RuneLocale *rl, _RuneRange *rr, _FileRuneRange *frr, void *lastp,
+readrange(_RuneLocale *rl, _RuneRange *rr, u_int32_t nranges, void *lastp,
FILE *fp)
{
- uint32_t i;
+ u_int32_t i;
_RuneEntry *re;
_FileRuneEntry fre;
re = (_RuneEntry *)rl->rl_variable;
- rr->rr_nranges = ntohl(frr->frr_nranges);
+ rr->rr_nranges = nranges;
if (rr->rr_nranges == 0) {
rr->rr_rune_ranges = NULL;
return 0;
@@ -92,6 +100,9 @@ readrange(_RuneLocale *rl, _RuneRange *r
rr->rr_rune_ranges = re;
for (i = 0; i < rr->rr_nranges; i++) {
+ if ((void *)re >= lastp)
+ return -1;
+
if (fread(&fre, sizeof(fre), 1, fp) != 1)
return -1;
@@ -99,9 +110,6 @@ readrange(_RuneLocale *rl, _RuneRange *r
re->re_max = ntohl((u_int32_t)fre.fre_max);
re->re_map = ntohl((u_int32_t)fre.fre_map);
re++;
-
- if ((void *)re > lastp)
- return -1;
}
rl->rl_variable = re;
return 0;
@@ -121,6 +129,9 @@ readentry(_RuneRange *rr, FILE *fp)
continue;
}
+ if (re[i].re_max < re[i].re_min)
+ goto fail;
+
l = re[i].re_max - re[i].re_min + 1;
re[i].re_rune_types = calloc(l, sizeof(_RuneType));
if (!re[i].re_rune_types) {
@@ -151,17 +162,20 @@ fail2:
}
/* XXX: temporary implementation */
-static void
+static int
find_codeset(_RuneLocale *rl)
{
char *top, *codeset, *tail, *ep;
+ if (rl->rl_variable == NULL)
+ return 0;
+
/* end of rl_variable region */
ep = (char *)rl->rl_variable;
ep += rl->rl_variable_len;
rl->rl_codeset = NULL;
if (!(top = strstr(rl->rl_variable, _RUNE_CODESET)))
- return;
+ return 0;
tail = strpbrk(top, " \t");
codeset = top + sizeof(_RUNE_CODESET) - 1;
if (tail) {
@@ -173,18 +187,18 @@ find_codeset(_RuneLocale *rl)
*top = '\0';
rl->rl_codeset = strdup(codeset);
}
+ return (rl->rl_codeset == NULL);
}
void
_freeentry(_RuneRange *rr)
{
_RuneEntry *re;
- uint32_t i;
+ u_int32_t i;
re = rr->rr_rune_ranges;
for (i = 0; i < rr->rr_nranges; i++) {
- if (re[i].re_rune_types)
- free(re[i].re_rune_types);
+ free(re[i].re_rune_types);
re[i].re_rune_types = NULL;
}
}
@@ -209,6 +223,7 @@ _Read_RuneMagi(FILE *fp)
_RuneLocale *rl;
struct stat sb;
int x;
+ u_int32_t runetype_nranges, maplower_nranges, mapupper_nranges, var_len;
if (fstat(fileno(fp), &sb) < 0)
return NULL;
@@ -225,10 +240,22 @@ _Read_RuneMagi(FILE *fp)
if (memcmp(frl.frl_magic, _RUNE_MAGIC_1, sizeof(frl.frl_magic)))
return NULL;
- hostdatalen = sizeof(*rl) + ntohl((u_int32_t)frl.frl_variable_len) +
- ntohl(frl.frl_runetype_ext.frr_nranges) * sizeof(_RuneEntry) +
- ntohl(frl.frl_maplower_ext.frr_nranges) * sizeof(_RuneEntry) +
- ntohl(frl.frl_mapupper_ext.frr_nranges) * sizeof(_RuneEntry);
+ runetype_nranges = ntohl(frl.frl_runetype_ext.frr_nranges);
+ maplower_nranges = ntohl(frl.frl_maplower_ext.frr_nranges);
+ mapupper_nranges = ntohl(frl.frl_mapupper_ext.frr_nranges);
+ var_len = ntohl((u_int32_t)frl.frl_variable_len);
+
+ if (runetype_nranges > SIZE_MAX / sizeof(_RuneEntry) ||
+ maplower_nranges > SIZE_MAX / sizeof(_RuneEntry) ||
+ mapupper_nranges > SIZE_MAX / sizeof(_RuneEntry) ||
+ (int32_t)var_len < 0)
+ return NULL;
+
+ hostdatalen = sizeof(*rl);
+ SAFE_ADD(hostdatalen, var_len);
+ SAFE_ADD(hostdatalen, runetype_nranges * sizeof(_RuneEntry));
+ SAFE_ADD(hostdatalen, maplower_nranges * sizeof(_RuneEntry));
+ SAFE_ADD(hostdatalen, mapupper_nranges * sizeof(_RuneEntry));
if ((hostdata = calloc(hostdatalen, 1)) == NULL)
return NULL;
@@ -240,6 +267,7 @@ _Read_RuneMagi(FILE *fp)
memcpy(rl->rl_magic, frl.frl_magic, sizeof(rl->rl_magic));
memcpy(rl->rl_encoding, frl.frl_encoding, sizeof(rl->rl_encoding));
+ /* XXX assumes rune_t = u_int32_t */
rl->rl_invalid_rune = ntohl((u_int32_t)frl.frl_invalid_rune);
rl->rl_variable_len = ntohl((u_int32_t)frl.frl_variable_len);
@@ -251,54 +279,39 @@ _Read_RuneMagi(FILE *fp)
rl->rl_mapupper[x] = ntohl((u_int32_t)frl.frl_mapupper[x]);
}
- if (readrange(rl, &rl->rl_runetype_ext, &frl.frl_runetype_ext, lastp,
fp))
- {
- free(hostdata);
- return NULL;
- }
- if (readrange(rl, &rl->rl_maplower_ext, &frl.frl_maplower_ext, lastp,
fp))
- {
- free(hostdata);
- return NULL;
- }
- if (readrange(rl, &rl->rl_mapupper_ext, &frl.frl_mapupper_ext, lastp,
fp))
- {
- free(hostdata);
- return NULL;
- }
+ if (readrange(rl, &rl->rl_runetype_ext, runetype_nranges, lastp, fp) ||
+ readrange(rl, &rl->rl_maplower_ext, maplower_nranges, lastp, fp) ||
+ readrange(rl, &rl->rl_mapupper_ext, mapupper_nranges, lastp, fp))
+ goto err;
- if (readentry(&rl->rl_runetype_ext, fp) != 0) {
- free(hostdata);
- return NULL;
- }
+ if (readentry(&rl->rl_runetype_ext, fp) != 0)
+ goto err;
if ((u_int8_t *)rl->rl_variable + rl->rl_variable_len >
- (u_int8_t *)lastp) {
- _freeentry(&rl->rl_runetype_ext);
- free(hostdata);
- return NULL;
- }
+ (u_int8_t *)lastp)
+ goto rune_err;
+
if (rl->rl_variable_len == 0)
rl->rl_variable = NULL;
- else if (fread(rl->rl_variable, rl->rl_variable_len, 1, fp) != 1) {
- _freeentry(&rl->rl_runetype_ext);
- free(hostdata);
- return NULL;
- }
- find_codeset(rl);
+ else if (fread(rl->rl_variable, rl->rl_variable_len, 1, fp) != 1)
+ goto rune_err;
+ if (find_codeset(rl))
+ goto rune_err;
_wctype_init(rl);
/*
* error if we have junk at the tail,
* or if we can't allocate memory.
*/
- if (ftell(fp) != sb.st_size || __make_ctype_tabs(rl) == -1) {
- _freeentry(&rl->rl_runetype_ext);
- free(hostdata);
- return NULL;
- }
+ if (ftello(fp) != sb.st_size || __make_ctype_tabs(rl) == -1)
+ goto rune_err;
return(rl);
+rune_err:
+ _freeentry(&rl->rl_runetype_ext);
+err:
+ free(hostdata);
+ return NULL;
}
void
