--- /dev/null
+From 167dfe9672c116b315e72e57a55c7769f180dffa Mon Sep 17 00:00:00 2001
+From: Rich Felker <dalias@aerifal.cx>
+Date: Thu, 20 Oct 2016 00:22:09 -0400
+Subject: fix integer overflows and uncaught EOVERFLOW in printf core
+
+this patch fixes a large number of missed internal signed-overflow
+checks and errors in determining when the return value (output length)
+would exceed INT_MAX, which should result in EOVERFLOW. some of the
+issues fixed were reported by Alexander Cherepanov; others were found
+in subsequent review of the code.
+
+aside from the signed overflows being undefined behavior, the
+following specific bugs were found to exist in practice:
+
+- overflows computing length of floating point formats with huge
+ explicit precisions, integer formats with prefix characters and huge
+ explicit precisions, or string arguments or format strings longer
+ than INT_MAX, resulted in wrong return value and wrong %n results.
+
+- literal width and precision values outside the range of int were
+ misinterpreted, yielding wrong behavior in at least one well-defined
+ case: string formats with precision greater than INT_MAX were
+ sometimes truncated.
+
+- in cases where EOVERFLOW is produced, incorrect values could be
+ written for %n specifiers past the point of exceeding INT_MAX.
+
+in addition to fixing these bugs, we now stop producing output
+immediately when output length would exceed INT_MAX, rather than
+continuing and returning an error only at the end.
+---
+ src/stdio/vfprintf.c | 72 +++++++++++++++++++++++++++++++++++----------------
+ src/stdio/vfwprintf.c | 63 +++++++++++++++++++++++++++-----------------
+ 2 files changed, 89 insertions(+), 46 deletions(-)
+
+diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
+index cd17ad7..e2ab2dc 100644
+--- a/src/stdio/vfprintf.c
++++ b/src/stdio/vfprintf.c
+@@ -272,6 +272,8 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
+ if (s-buf==1 && (y||p>0||(fl&ALT_FORM))) *s++='.';
+ } while (y);
+
++ if (p > INT_MAX-2-(ebuf-estr)-pl)
++ return -1;
+ if (p && s-buf-2 < p)
+ l = (p+2) + (ebuf-estr);
+ else
+@@ -383,17 +385,22 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
+ p = MIN(p,MAX(0,9*(z-r-1)+e-j));
+ }
+ }
++ if (p > INT_MAX-1-(p || (fl&ALT_FORM)))
++ return -1;
+ l = 1 + p + (p || (fl&ALT_FORM));
+ if ((t|32)=='f') {
++ if (e > INT_MAX-l) return -1;
+ if (e>0) l+=e;
+ } else {
+ estr=fmt_u(e<0 ? -e : e, ebuf);
+ while(ebuf-estr<2) *--estr='0';
+ *--estr = (e<0 ? '-' : '+');
+ *--estr = t;
++ if (ebuf-estr > INT_MAX-l) return -1;
+ l += ebuf-estr;
+ }
+
++ if (l > INT_MAX-pl) return -1;
+ pad(f, ' ', w, pl+l, fl);
+ out(f, prefix, pl);
+ pad(f, '0', w, pl+l, fl^ZERO_PAD);
+@@ -437,8 +444,10 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
+
+ static int getint(char **s) {
+ int i;
+- for (i=0; isdigit(**s); (*s)++)
+- i = 10*i + (**s-'0');
++ for (i=0; isdigit(**s); (*s)++) {
++ if (i > INT_MAX/10U || **s-'0' > INT_MAX-10*i) i = -1;
++ else i = 10*i + (**s-'0');
++ }
+ return i;
+ }
+
+@@ -446,12 +455,12 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ {
+ char *a, *z, *s=(char *)fmt;
+ unsigned l10n=0, fl;
+- int w, p;
++ int w, p, xp;
+ union arg arg;
+ int argpos;
+ unsigned st, ps;
+ int cnt=0, l=0;
+- int i;
++ size_t i;
+ char buf[sizeof(uintmax_t)*3+3+LDBL_MANT_DIG/4];
+ const char *prefix;
+ int t, pl;
+@@ -459,18 +468,19 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ char mb[4];
+
+ for (;;) {
++ /* This error is only specified for snprintf, but since it's
++ * unspecified for other forms, do the same. Stop immediately
++ * on overflow; otherwise %n could produce wrong results. */
++ if (l > INT_MAX - cnt) goto overflow;
++
+ /* Update output count, end loop when fmt is exhausted */
+- if (cnt >= 0) {
+- if (l > INT_MAX - cnt) {
+- errno = EOVERFLOW;
+- cnt = -1;
+- } else cnt += l;
+- }
++ cnt += l;
+ if (!*s) break;
+
+ /* Handle literal text and %% format specifiers */
+ for (a=s; *s && *s!='%'; s++);
+ for (z=s; s[0]=='%' && s[1]=='%'; z++, s+=2);
++ if (z-a > INT_MAX-cnt) goto overflow;
+ l = z-a;
+ if (f) out(f, a, l);
+ if (l) continue;
+@@ -498,9 +508,9 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ } else if (!l10n) {
+ w = f ? va_arg(*ap, int) : 0;
+ s++;
+- } else return -1;
++ } else goto inval;
+ if (w<0) fl|=LEFT_ADJ, w=-w;
+- } else if ((w=getint(&s))<0) return -1;
++ } else if ((w=getint(&s))<0) goto overflow;
+
+ /* Read precision */
+ if (*s=='.' && s[1]=='*') {
+@@ -511,24 +521,29 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ } else if (!l10n) {
+ p = f ? va_arg(*ap, int) : 0;
+ s+=2;
+- } else return -1;
++ } else goto inval;
++ xp = (p>=0);
+ } else if (*s=='.') {
+ s++;
+ p = getint(&s);
+- } else p = -1;
++ xp = 1;
++ } else {
++ p = -1;
++ xp = 0;
++ }
+
+ /* Format specifier state machine */
+ st=0;
+ do {
+- if (OOB(*s)) return -1;
++ if (OOB(*s)) goto inval;
+ ps=st;
+ st=states[st]S(*s++);
+ } while (st-1<STOP);
+- if (!st) return -1;
++ if (!st) goto inval;
+
+ /* Check validity of argument type (nl/normal) */
+ if (st==NOARG) {
+- if (argpos>=0) return -1;
++ if (argpos>=0) goto inval;
+ } else {
+ if (argpos>=0) nl_type[argpos]=st, arg=nl_arg[argpos];
+ else if (f) pop_arg(&arg, st, ap);
+@@ -584,6 +599,7 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ case 'u':
+ a = fmt_u(arg.i, z);
+ }
++ if (xp && p<0) goto overflow;
+ if (p>=0) fl &= ~ZERO_PAD;
+ if (!arg.i && !p) {
+ a=z;
+@@ -599,9 +615,9 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ if (1) a = strerror(errno); else
+ case 's':
+ a = arg.p ? arg.p : "(null)";
+- z = memchr(a, 0, p);
+- if (!z) z=a+p;
+- else p=z-a;
++ z = a + strnlen(a, p<0 ? INT_MAX : p);
++ if (p<0 && *z) goto overflow;
++ p = z-a;
+ fl &= ~ZERO_PAD;
+ break;
+ case 'C':
+@@ -611,8 +627,9 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ p = -1;
+ case 'S':
+ ws = arg.p;
+- for (i=l=0; i<0U+p && *ws && (l=wctomb(mb, *ws++))>=0 && l<=0U+p-i; i+=l);
++ for (i=l=0; i<p && *ws && (l=wctomb(mb, *ws++))>=0 && l<=p-i; i+=l);
+ if (l<0) return -1;
++ if (i > INT_MAX) goto overflow;
+ p = i;
+ pad(f, ' ', w, p, fl);
+ ws = arg.p;
+@@ -623,12 +640,16 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ continue;
+ case 'e': case 'f': case 'g': case 'a':
+ case 'E': case 'F': case 'G': case 'A':
++ if (xp && p<0) goto overflow;
+ l = fmt_fp(f, arg.f, w, p, fl, t);
++ if (l<0) goto overflow;
+ continue;
+ }
+
+ if (p < z-a) p = z-a;
++ if (p > INT_MAX-pl) goto overflow;
+ if (w < pl+p) w = pl+p;
++ if (w > INT_MAX-cnt) goto overflow;
+
+ pad(f, ' ', w, pl+p, fl);
+ out(f, prefix, pl);
+@@ -646,8 +667,15 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
+ for (i=1; i<=NL_ARGMAX && nl_type[i]; i++)
+ pop_arg(nl_arg+i, nl_type[i], ap);
+ for (; i<=NL_ARGMAX && !nl_type[i]; i++);
+- if (i<=NL_ARGMAX) return -1;
++ if (i<=NL_ARGMAX) goto inval;
+ return 1;
++
++inval:
++ errno = EINVAL;
++ return -1;
++overflow:
++ errno = EOVERFLOW;
++ return -1;
+ }
+
+ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
+diff --git a/src/stdio/vfwprintf.c b/src/stdio/vfwprintf.c
+index f9f1ecf..b8fff20 100644
+--- a/src/stdio/vfwprintf.c
++++ b/src/stdio/vfwprintf.c
+@@ -154,8 +154,10 @@ static void out(FILE *f, const wchar_t *s, size_t l)
+
+ static int getint(wchar_t **s) {
+ int i;
+- for (i=0; iswdigit(**s); (*s)++)
+- i = 10*i + (**s-'0');
++ for (i=0; iswdigit(**s); (*s)++) {
++ if (i > INT_MAX/10U || **s-'0' > INT_MAX-10*i) i = -1;
++ else i = 10*i + (**s-'0');
++ }
+ return i;
+ }
+
+@@ -168,8 +170,8 @@ static const char sizeprefix['y'-'a'] = {
+ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_arg, int *nl_type)
+ {
+ wchar_t *a, *z, *s=(wchar_t *)fmt;
+- unsigned l10n=0, litpct, fl;
+- int w, p;
++ unsigned l10n=0, fl;
++ int w, p, xp;
+ union arg arg;
+ int argpos;
+ unsigned st, ps;
+@@ -181,20 +183,19 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ wchar_t wc;
+
+ for (;;) {
++ /* This error is only specified for snprintf, but since it's
++ * unspecified for other forms, do the same. Stop immediately
++ * on overflow; otherwise %n could produce wrong results. */
++ if (l > INT_MAX - cnt) goto overflow;
++
+ /* Update output count, end loop when fmt is exhausted */
+- if (cnt >= 0) {
+- if (l > INT_MAX - cnt) {
+- if (!ferror(f)) errno = EOVERFLOW;
+- cnt = -1;
+- } else cnt += l;
+- }
++ cnt += l;
+ if (!*s) break;
+
+ /* Handle literal text and %% format specifiers */
+ for (a=s; *s && *s!='%'; s++);
+- litpct = wcsspn(s, L"%")/2; /* Optimize %%%% runs */
+- z = s+litpct;
+- s += 2*litpct;
++ for (z=s; s[0]=='%' && s[1]=='%'; z++, s+=2);
++ if (z-a > INT_MAX-cnt) goto overflow;
+ l = z-a;
+ if (f) out(f, a, l);
+ if (l) continue;
+@@ -222,9 +223,9 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ } else if (!l10n) {
+ w = f ? va_arg(*ap, int) : 0;
+ s++;
+- } else return -1;
++ } else goto inval;
+ if (w<0) fl|=LEFT_ADJ, w=-w;
+- } else if ((w=getint(&s))<0) return -1;
++ } else if ((w=getint(&s))<0) goto overflow;
+
+ /* Read precision */
+ if (*s=='.' && s[1]=='*') {
+@@ -235,24 +236,29 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ } else if (!l10n) {
+ p = f ? va_arg(*ap, int) : 0;
+ s+=2;
+- } else return -1;
++ } else goto inval;
++ xp = (p>=0);
+ } else if (*s=='.') {
+ s++;
+ p = getint(&s);
+- } else p = -1;
++ xp = 1;
++ } else {
++ p = -1;
++ xp = 0;
++ }
+
+ /* Format specifier state machine */
+ st=0;
+ do {
+- if (OOB(*s)) return -1;
++ if (OOB(*s)) goto inval;
+ ps=st;
+ st=states[st]S(*s++);
+ } while (st-1<STOP);
+- if (!st) return -1;
++ if (!st) goto inval;
+
+ /* Check validity of argument type (nl/normal) */
+ if (st==NOARG) {
+- if (argpos>=0) return -1;
++ if (argpos>=0) goto inval;
+ } else {
+ if (argpos>=0) nl_type[argpos]=st, arg=nl_arg[argpos];
+ else if (f) pop_arg(&arg, st, ap);
+@@ -285,8 +291,9 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ continue;
+ case 'S':
+ a = arg.p;
+- z = wmemchr(a, 0, p);
+- if (z) p=z-a;
++ z = a + wcsnlen(a, p<0 ? INT_MAX : p);
++ if (p<0 && *z) goto overflow;
++ p = z-a;
+ if (w<p) w=p;
+ if (!(fl&LEFT_ADJ)) fprintf(f, "%*s", w-p, "");
+ out(f, a, p);
+@@ -298,9 +305,9 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ case 's':
+ if (!arg.p) arg.p = "(null)";
+ bs = arg.p;
+- if (p<0) p = INT_MAX;
+- for (i=l=0; l<p && (i=mbtowc(&wc, bs, MB_LEN_MAX))>0; bs+=i, l++);
++ for (i=l=0; l<(p<0?INT_MAX:p) && (i=mbtowc(&wc, bs, MB_LEN_MAX))>0; bs+=i, l++);
+ if (i<0) return -1;
++ if (p<0 && *bs) goto overflow;
+ p=l;
+ if (w<p) w=p;
+ if (!(fl&LEFT_ADJ)) fprintf(f, "%*s", w-p, "");
+@@ -315,6 +322,7 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ continue;
+ }
+
++ if (xp && p<0) goto overflow;
+ snprintf(charfmt, sizeof charfmt, "%%%s%s%s%s%s*.*%c%c",
+ "#"+!(fl & ALT_FORM),
+ "+"+!(fl & MARK_POS),
+@@ -341,6 +349,13 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
+ for (; i<=NL_ARGMAX && !nl_type[i]; i++);
+ if (i<=NL_ARGMAX) return -1;
+ return 1;
++
++inval:
++ errno = EINVAL;
++ return -1;
++overflow:
++ errno = EOVERFLOW;
++ return -1;
+ }
+
+ int vfwprintf(FILE *restrict f, const wchar_t *restrict fmt, va_list ap)
+--
+cgit v0.11.2
projects / openwrt / staging / lynxis / omap.git / blobdiff