From: Paul Eggert Date: Fri, 13 May 2011 06:12:24 +0000 (-0700) Subject: * editfns.c (Fformat): Fix several integer overflow problems. X-Git-Tag: emacs-pretest-24.0.90~104^2~618^2~239^2~23^2~3 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=2d165e9dc58924db64f73791a638c136bc6324d7;p=emacs.git * editfns.c (Fformat): Fix several integer overflow problems. For example, without this change, (format "%2147483648d" 1) dumps core on x86-64 GNU/Linux. Use EMACS_INT, not size_t, for sizes, since we prefer using signed values, and EMACS_INT will be big enough soon, even on 32-bit hosts. Also, prefer EMACS_INT to int for sizes. Don't assume that pI is either "l" or ""; it might be "ll" or "I64". Check for width and precision greater than INT_MAX, as this can make sprintf go kaflooey. (Bug#8668) --- diff --git a/src/ChangeLog b/src/ChangeLog index 378d8a22808..9bdbb9a7d18 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,5 +1,14 @@ 2011-05-13 Paul Eggert + * editfns.c (Fformat): Fix several integer overflow problems. + For example, without this change, (format "%2147483648d" 1) dumps + core on x86-64 GNU/Linux. Use EMACS_INT, not size_t, for sizes, + since we prefer using signed values, and EMACS_INT will be big + enough soon, even on 32-bit hosts. Also, prefer EMACS_INT to int + for sizes. Don't assume that pI is either "l" or ""; it might be + "ll" or "I64". Check for width and precision greater than + INT_MAX, as this can make sprintf go kaflooey. (Bug#8668) + * dispextern.h (struct image): Don't assume time_t <= unsigned long. * image.c (clear_image_cache): Likewise. diff --git a/src/editfns.c b/src/editfns.c index 5e1dcce0275..b5ccb481c43 100644 --- a/src/editfns.c +++ b/src/editfns.c @@ -3583,11 +3583,12 @@ specifier truncates the string to the given width. usage: (format STRING &rest OBJECTS) */) (size_t nargs, register Lisp_Object *args) { - register size_t n; /* The number of the next arg to substitute */ - register size_t total; /* An estimate of the final length */ + register EMACS_INT n; /* The number of the next arg to substitute */ + register EMACS_INT total; /* An estimate of the final length */ + int pIlen = sizeof pI - 1; char *buf, *p; register char *format, *end, *format_start; - int nchars; + EMACS_INT nchars; /* Nonzero if the output should be a multibyte string, which is true if any of the inputs is one. */ int multibyte = 0; @@ -3603,7 +3604,7 @@ usage: (format STRING &rest OBJECTS) */) no argument, *will* be assigned to in the case that a `%' and `.' occur after the final format specifier. */ int *precision = (int *) (alloca ((nargs + 1) * sizeof (int))); - int longest_format; + EMACS_INT longest_format; Lisp_Object val; int arg_intervals = 0; USE_SAFE_ALLOCA; @@ -3619,7 +3620,8 @@ usage: (format STRING &rest OBJECTS) */) info[0] is unused. Unused elements have -1 for start. */ struct info { - int start, end, intervals; + EMACS_INT start, end; + int intervals; } *info = 0; /* It should not be necessary to GCPRO ARGS, because @@ -3660,8 +3662,8 @@ usage: (format STRING &rest OBJECTS) */) /* Allocate the info and discarded tables. */ { - size_t nbytes = (nargs+1) * sizeof *info; - size_t i; + EMACS_INT nbytes = (nargs + 1) * sizeof *info; + EMACS_INT i; if (!info) info = (struct info *) alloca (nbytes); memset (info, 0, nbytes); @@ -3706,25 +3708,33 @@ usage: (format STRING &rest OBJECTS) */) || * format == ' ' || *format == '+')) ++format; + /* Parse width and precision, limiting them to the range of 'int' + because otherwise the underyling sprintf may go kaflooey. */ + if (*format >= '0' && *format <= '9') { - for (field_width = 0; *format >= '0' && *format <= '9'; ++format) - field_width = 10 * field_width + *format - '0'; + char *width_end; + unsigned long width = strtoul (format, &width_end, 10); + if (INT_MAX < width) + error ("Format string field width too large"); + field_width = width; + format = width_end; } /* N is not incremented for another few lines below, so refer to element N+1 (which might be precision[NARGS]). */ if (*format == '.') { - ++format; - for (precision[n+1] = 0; *format >= '0' && *format <= '9'; ++format) - precision[n+1] = 10 * precision[n+1] + *format - '0'; + char *prec_end; + unsigned long prec = strtoul (format + 1, &prec_end, 10); + if (INT_MAX < prec) + error ("Format string precision too large"); + precision[n + 1] = prec; + format = prec_end; } - /* Extra +1 for 'l' that we may need to insert into the - format. */ - if (format - this_format_start + 2 > longest_format) - longest_format = format - this_format_start + 2; + if (longest_format < format - this_format_start + pIlen + 1) + longest_format = format - this_format_start + pIlen + 1; if (format == end) error ("Format string ends in middle of format specifier"); @@ -3975,24 +3985,22 @@ usage: (format STRING &rest OBJECTS) */) } else if (INTEGERP (args[n]) || FLOATP (args[n])) { - int this_nchars; + EMACS_INT this_nchars; + EMACS_INT this_format_len = format - this_format_start; - memcpy (this_format, this_format_start, - format - this_format_start); - this_format[format - this_format_start] = 0; + memcpy (this_format, this_format_start, this_format_len); + this_format[this_format_len] = 0; if (format[-1] == 'e' || format[-1] == 'f' || format[-1] == 'g') sprintf (p, this_format, XFLOAT_DATA (args[n])); else { - if (sizeof (EMACS_INT) > sizeof (int) - && format[-1] != 'c') + if (pIlen && format[-1] != 'c') { - /* Insert 'l' before format spec. */ - this_format[format - this_format_start] - = this_format[format - this_format_start - 1]; - this_format[format - this_format_start - 1] = 'l'; - this_format[format - this_format_start + 1] = 0; + /* Insert pI before format spec. */ + memcpy (&this_format[this_format_len - 1], pI, pIlen); + this_format[this_format_len + pIlen - 1] = format[-1]; + this_format[this_format_len + pIlen] = 0; } if (INTEGERP (args[n])) @@ -4089,7 +4097,7 @@ usage: (format STRING &rest OBJECTS) */) if (CONSP (props)) { EMACS_INT bytepos = 0, position = 0, translated = 0; - int argn = 1; + EMACS_INT argn = 1; Lisp_Object list; /* Adjust the bounds of each text property