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Issue 296 - Avoid potential buffer overflow.

This commit is contained in:
wb2osz 2020-11-05 18:51:00 -05:00
parent bfc708d014
commit 4a1aa2b148
2 changed files with 50 additions and 6 deletions
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11
src/encode_aprs.c
View File

@ -81,8 +81,14 @@ typedef struct position_s {
static int set_norm_position (char symtab, char symbol, double dlat, double dlong, int ambiguity, position_t *presult)
{
// An over zealous compiler might complain about l*itude_to_str writing
// N characters plus nul to an N character field so we stick it into a
// larger temp then copy the desired number of bytes. (Issue 296)
latitude_to_str (dlat, ambiguity, presult->lat);
char stemp[16];
latitude_to_str (dlat, ambiguity, stemp);
memcpy (presult->lat, stemp, sizeof(presult->lat));
if (symtab != '/' && symtab != '\\' && ! isdigit(symtab) && ! isupper(symtab)) {
text_color_set(DW_COLOR_ERROR);
@ -90,7 +96,8 @@ static int set_norm_position (char symtab, char symbol, double dlat, double dlon
}
presult->sym_table_id = symtab;
longitude_to_str (dlong, ambiguity, presult->lon);
longitude_to_str (dlong, ambiguity, stemp);
memcpy (presult->lon, stemp, sizeof(presult->lon));
if (symbol < '!' || symbol > '~') {
text_color_set(DW_COLOR_ERROR);

45
src/latlong.c
View File

@ -55,7 +55,11 @@
* ambiguity - If 1, 2, 3, or 4, blank out that many trailing digits.
*
* Outputs: slat - String in format ddmm.mm[NS]
* Should always be exactly 8 characters + NUL.
* Must always be exactly 8 characters + NUL.
* Put in leading zeros if necessary.
* We must have exactly ddmm.mm and hemisphere because
* the APRS position report has fixed width fields.
* Trailing digits can be blanked for position ambiguity.
*
* Returns: None
*
@ -101,6 +105,12 @@ void latitude_to_str (double dlat, int ambiguity, char *slat)
ideg = (int)dlat;
dmin = (dlat - ideg) * 60.;
// dmin is known to be in range of 0 <= dmin < 60.
// Minutes must be exactly like 99.99 with leading zeros,
// if needed, to make it fixed width.
// Two digits, decimal point, two digits, nul terminator.
snprintf (smin, sizeof(smin), "%05.2f", dmin);
/* Due to roundoff, 59.9999 could come out as "60.00" */
if (smin[0] == '6') {
@ -108,6 +118,9 @@ void latitude_to_str (double dlat, int ambiguity, char *slat)
ideg++;
}
// Assumes slat can hold 8 characters + nul.
// Degrees must be exactly 2 digits, with leading zero, if needed.
sprintf (slat, "%02d%s%c", ideg, smin, hemi);
if (ambiguity >= 1) {
@ -135,9 +148,12 @@ void latitude_to_str (double dlat, int ambiguity, char *slat)
* Inputs: dlong - Floating point degrees.
* ambiguity - If 1, 2, 3, or 4, blank out that many trailing digits.
*
* Outputs: slat - String in format dddmm.mm[NS]
* Should always be exactly 9 characters + NUL.
*
* Outputs: slong - String in format dddmm.mm[NS]
* Must always be exactly 9 characters + NUL.
* Put in leading zeros if necessary.
* We must have exactly dddmm.mm and hemisphere because
* the APRS position report has fixed width fields.
* Trailing digits can be blanked for position ambiguity.
* Returns: None
*
*----------------------------------------------------------------*/
@ -178,7 +194,11 @@ void longitude_to_str (double dlong, int ambiguity, char *slong)
ideg++;
}
// Assumes slong can hold 9 characters + nul.
// Degrees must be exactly 3 digits, with leading zero, if needed.
sprintf (slong, "%03d%s%c", ideg, smin, hemi);
/*
* The spec says position ambiguity in latitude also
* applies to longitude automatically.
@ -903,6 +923,14 @@ int main (int argc, char *argv[])
latitude_to_str (45.999830, 4, result);
if (strcmp(result, "45 . N") != 0) { errors++; dw_printf ("Error 1.8: Did not expect \"%s\"\n", result); }
// Test for leading zeros for small values. Result must be fixed width.
latitude_to_str (0.016666666, 0, result);
if (strcmp(result, "0001.00N") != 0) { errors++; dw_printf ("Error 1.9: Did not expect \"%s\"\n", result); }
latitude_to_str (-1.999999, 0, result);
if (strcmp(result, "0200.00S") != 0) { errors++; dw_printf ("Error 1.10: Did not expect \"%s\"\n", result); }
/* Longitude to APRS format. */
longitude_to_str (45.25, 0, result);
@ -931,6 +959,15 @@ int main (int argc, char *argv[])
longitude_to_str (45.999830, 4, result);
if (strcmp(result, "045 . E") != 0) { errors++; dw_printf ("Error 2.8: Did not expect \"%s\"\n", result); }
// Test for leading zeros for small values. Result must be fixed width.
longitude_to_str (0.016666666, 0, result);
if (strcmp(result, "00001.00E") != 0) { errors++; dw_printf ("Error 2.9: Did not expect \"%s\"\n", result); }
longitude_to_str (-1.999999, 0, result);
if (strcmp(result, "00200.00W") != 0) { errors++; dw_printf ("Error 2.10: Did not expect \"%s\"\n", result); }
/* Compressed format. */
/* Protocol spec example has <*e7 but I got <*e8 due to rounding rather than truncation to integer. */