patch 9.0.2142: [security]: stack-buffer-overflow in option callback functions
Problem: [security]: stack-buffer-overflow in option callback functions
Solution: pass size of errbuf down the call stack, use snprintf()
instead of sprintf()
We pass the error buffer down to the option callback functions, but in
some parts of the code, we simply use sprintf(buf) to write into the error
buffer, which can overflow.
So let's pass down the length of the error buffer and use sprintf(buf, size)
instead.
Reported by @henices, thanks!
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/optionstr.c b/src/optionstr.c
index b7cdcc4..84c77cb 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -229,11 +229,12 @@
#endif
static char *
-illegal_char(char *errbuf, int c)
+illegal_char(char *errbuf, int errbuflen, int c)
{
if (errbuf == NULL)
return "";
- sprintf((char *)errbuf, _(e_illegal_character_str), (char *)transchar(c));
+ snprintf((char *)errbuf, errbuflen, _(e_illegal_character_str),
+ (char *)transchar(c));
return errbuf;
}
@@ -525,7 +526,8 @@
int opt_idx,
char_u *value,
int opt_flags, // OPT_LOCAL and/or OPT_GLOBAL
- char *errbuf)
+ char *errbuf,
+ int errbuflen)
{
char_u *s;
char_u **varp;
@@ -579,7 +581,7 @@
}
#endif
if ((errmsg = did_set_string_option(opt_idx, varp, oldval, value, errbuf,
- opt_flags, OP_NONE, &value_checked)) == NULL)
+ errbuflen, opt_flags, OP_NONE, &value_checked)) == NULL)
did_set_option(opt_idx, opt_flags, TRUE, value_checked);
#if defined(FEAT_EVAL)
@@ -615,7 +617,8 @@
check_stl_option(char_u *s)
{
int groupdepth = 0;
- static char errbuf[80];
+ static char errbuf[ERR_BUFLEN];
+ int errbuflen = ERR_BUFLEN;
while (*s)
{
@@ -656,7 +659,7 @@
}
if (vim_strchr(STL_ALL, *s) == NULL)
{
- return illegal_char(errbuf, *s);
+ return illegal_char(errbuf, errbuflen, *s);
}
if (*s == '{')
{
@@ -664,7 +667,7 @@
if (reevaluate && *++s == '}')
// "}" is not allowed immediately after "%{%"
- return illegal_char(errbuf, '}');
+ return illegal_char(errbuf, errbuflen, '}');
while ((*s != '}' || (reevaluate && s[-1] != '%')) && *s)
s++;
if (*s != '}')
@@ -719,13 +722,17 @@
* An option which is a list of flags is set. Valid values are in 'flags'.
*/
static char *
-did_set_option_listflag(char_u *val, char_u *flags, char *errbuf)
+did_set_option_listflag(
+ char_u *val,
+ char_u *flags,
+ char *errbuf,
+ int errbuflen)
{
char_u *s;
for (s = val; *s; ++s)
if (vim_strchr(flags, *s) == NULL)
- return illegal_char(errbuf, *s);
+ return illegal_char(errbuf, errbuflen, *s);
return NULL;
}
@@ -1461,7 +1468,7 @@
if (vim_strchr((char_u *)COM_ALL, *s) == NULL
&& !VIM_ISDIGIT(*s) && *s != '-')
{
- errmsg = illegal_char(args->os_errbuf, *s);
+ errmsg = illegal_char(args->os_errbuf, args->os_errbuflen, *s);
break;
}
++s;
@@ -1517,7 +1524,7 @@
if (!*s)
break;
if (vim_strchr((char_u *)".wbuksid]tU", *s) == NULL)
- return illegal_char(args->os_errbuf, *s);
+ return illegal_char(args->os_errbuf, args->os_errbuflen, *s);
if (*++s != NUL && *s != ',' && *s != ' ')
{
if (s[-1] == 'k' || s[-1] == 's')
@@ -1534,7 +1541,7 @@
{
if (args->os_errbuf != NULL)
{
- sprintf((char *)args->os_errbuf,
+ snprintf((char *)args->os_errbuf, args->os_errbuflen,
_(e_illegal_character_after_chr), *--s);
return args->os_errbuf;
}
@@ -1634,7 +1641,8 @@
{
char_u **varp = (char_u **)args->os_varp;
- return did_set_option_listflag(*varp, (char_u *)COCU_ALL, args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)COCU_ALL, args->os_errbuf,
+ args->os_errbuflen);
}
int
@@ -1652,7 +1660,8 @@
{
char_u **varp = (char_u **)args->os_varp;
- return did_set_option_listflag(*varp, (char_u *)CPO_ALL, args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)CPO_ALL, args->os_errbuf,
+ args->os_errbuflen);
}
int
@@ -2281,7 +2290,8 @@
{
char_u **varp = (char_u **)args->os_varp;
- return did_set_option_listflag(*varp, (char_u *)FO_ALL, args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)FO_ALL, args->os_errbuf,
+ args->os_errbuflen);
}
int
@@ -2422,7 +2432,8 @@
char_u **varp = (char_u **)args->os_varp;
char *errmsg;
- errmsg = did_set_option_listflag(*varp, (char_u *)GO_ALL, args->os_errbuf);
+ errmsg = did_set_option_listflag(*varp, (char_u *)GO_ALL, args->os_errbuf,
+ args->os_errbuflen);
if (errmsg != NULL)
return errmsg;
@@ -2926,8 +2937,8 @@
{
char_u **varp = (char_u **)args->os_varp;
- return did_set_option_listflag(*varp, (char_u *)MOUSE_ALL,
- args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)MOUSE_ALL, args->os_errbuf,
+ args->os_errbuflen);
}
int
@@ -3364,7 +3375,8 @@
{
char_u **varp = (char_u **)args->os_varp;
- return did_set_option_listflag(*varp, (char_u *)SHM_ALL, args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)SHM_ALL, args->os_errbuf,
+ args->os_errbuflen);
}
int
@@ -4030,7 +4042,7 @@
// Check it's a valid character
if (vim_strchr((char_u *)"!\"%'/:<@cfhnrs", *s) == NULL)
{
- errmsg = illegal_char(args->os_errbuf, *s);
+ errmsg = illegal_char(args->os_errbuf, args->os_errbuflen, *s);
break;
}
if (*s == 'n') // name is always last one
@@ -4057,7 +4069,7 @@
{
if (args->os_errbuf != NULL)
{
- sprintf(args->os_errbuf,
+ snprintf(args->os_errbuf, args->os_errbuflen,
_(e_missing_number_after_angle_str_angle),
transchar_byte(*(s - 1)));
errmsg = args->os_errbuf;
@@ -4140,7 +4152,8 @@
// Add ',' to the list flags because 'whichwrap' is a flag
// list that is comma-separated.
- return did_set_option_listflag(*varp, (char_u *)(WW_ALL ","), args->os_errbuf);
+ return did_set_option_listflag(*varp, (char_u *)(WW_ALL ","),
+ args->os_errbuf, args->os_errbuflen);
}
int
@@ -4341,6 +4354,7 @@
char_u *oldval, // previous value of the option
char_u *value, // new value of the option
char *errbuf, // buffer for errors, or NULL
+ int errbuflen, // length of error buffer
int opt_flags, // OPT_LOCAL and/or OPT_GLOBAL
set_op_T op, // OP_ADDING/OP_PREPENDING/OP_REMOVING
int *value_checked) // value was checked to be safe, no
@@ -4385,6 +4399,7 @@
args.os_oldval.string = oldval;
args.os_newval.string = value;
args.os_errbuf = errbuf;
+ args.os_errbuflen = errbuflen;
// Invoke the option specific callback function to validate and apply
// the new option value.
errmsg = did_set_cb(&args);