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fix pline.c potential buffer overruns

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Fix 'Bugs 4, 5, and 6' which all use a similar fix but would have
conflicts over '#define BIGBUFSZ' if committed separately.

Format ("short explanation %s", string_argument), where the
explanation always has modest length but the string is potentially
up to 4*BUFSZ in length, into a 5*BUFSZ buffer.  Then truncate the
result to at most BUFSZ-1 characters so that it can be safely passed
to interface-specific putstr() or raw_print().

Applies to pline(), raw_printf(), and config_error_add().  Also done
for impossible() although there's no evidence that its buffer could
be overflowed in a controlled manner.
This commit is contained in:
PatR
2020-01-14 02:52:34 -08:00
parent 74de7d31e0
commit cdc598e8bd
2 changed files with 10 additions and 6 deletions
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1
doc/fixes36.5
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@@ -10,6 +10,7 @@ have string_for_opt() return empty_optstr on failure
ensure existing callers of string_for_opt() check return value before using it
fix potential buffer overflow in add_menu_coloring()
fix potential buffer overflow in sym_val()
fix potential buffer overflow in pline(), raw_printf(), and config_error_add()
Fixes to Post-3.6.4 Problems that Were Exposed Via git Repository

15
src/pline.c
View File

@@ -6,6 +6,10 @@
#define NEED_VARARGS /* Uses ... */ /* comment line for pre-compiled headers */
#include "hack.h"
#define BIGBUFSZ (5 * BUFSZ) /* big enough to format a 4*BUFSZ string (from
* config file parsing) with modest decoration;
* result will then be truncated to BUFSZ-1 */
static unsigned pline_flags = 0;
static char prevmsg[BUFSZ];
@@ -118,7 +122,7 @@ VA_DECL(const char *, line)
#endif /* USE_STDARG | USE_VARARG */
{ /* start of vpline() or of nested block in USE_OLDARG's pline() */
static int in_pline = 0;
char pbuf[3 * BUFSZ];
char pbuf[BIGBUFSZ]; /* will get chopped down to BUFSZ-1 if longer */
int ln;
int msgtyp;
boolean no_repeat;
@@ -443,15 +447,14 @@ void raw_printf
VA_DECL(const char *, line)
#endif
{
char pbuf[3 * BUFSZ];
int ln;
char pbuf[BIGBUFSZ]; /* will be chopped down to BUFSZ-1 if longer */
/* Do NOT use VA_START and VA_END in here... see above */
if (index(line, '%')) {
Vsprintf(pbuf, line, VA_ARGS);
line = pbuf;
}
if ((ln = (int) strlen(line)) > BUFSZ - 1) {
if ((int) strlen(line) > BUFSZ - 1) {
if (line != pbuf)
line = strncpy(pbuf, line, BUFSZ - 1);
/* unlike pline, we don't futz around to keep last few chars */
@@ -470,7 +473,7 @@ VA_DECL(const char *, line)
void impossible
VA_DECL(const char *, s)
{
char pbuf[2 * BUFSZ];
char pbuf[BIGBUFSZ]; /* will be chopped down to BUFSZ-1 if longer */
VA_START(s);
VA_INIT(s, const char *);
@@ -571,7 +574,7 @@ config_error_add
VA_DECL(const char *, str)
#endif /* ?(USE_STDARG || USE_VARARG) */
{ /* start of vconf...() or of nested block in USE_OLDARG's conf...() */
char buf[2 * BUFSZ];
char buf[BIGBUFSZ]; /* will be chopped down to BUFSZ-1 if longer */
Vsprintf(buf, str, VA_ARGS);
buf[BUFSZ - 1] = '\0';