Wednesday, January 31, 2018

[389-commits] [389-ds-base] 01/01: CVE-2017-15134 389-ds-base: Remote DoS via search filters in slapi_filter_sprintf

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lkrispen pushed a commit to branch master
in repository 389-ds-base.

commit 6aa2acdc3cad97ebec2a6d59d479a15e89bbb3a0
Author: Ludwig Krispenz <lkrispen@redhat.com>
Date: Mon Jan 15 10:24:41 2018 +0100

CVE-2017-15134 389-ds-base: Remote DoS via search filters in
slapi_filter_sprintf

Description: Improper handling of a search filter in slapi_filter_sprintf
in slapd/util.c can lead to remote server crash and denial
of service.
---
ldap/servers/slapd/util.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/ldap/servers/slapd/util.c b/ldap/servers/slapd/util.c
index a72de9b..ddb2cc8 100644
--- a/ldap/servers/slapd/util.c
+++ b/ldap/servers/slapd/util.c
@@ -238,9 +238,10 @@ escape_string_for_filename(const char *str, char buf[BUFSIZ])
struct filter_ctx
{
char *buf;
- char attr[ATTRSIZE];
+ char *attr;
int attr_position;
int attr_found;
+ size_t attr_size;
int buf_size;
int buf_len;
int next_arg_needs_esc_norm;
@@ -279,7 +280,7 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
* Start collecting the attribute name so we can use the correct
* syntax normalization func.
*/
- if (ctx->attr_found == 0 && ctx->attr_position < (ATTRSIZE - 1)) {
+ if (ctx->attr_found == 0 && ctx->attr_position < (ctx->attr_size - 1)) {
if (ctx->attr[0] == '\0') {
if (strstr(val, "=")) {
/* we have an attr we need to record */
@@ -293,6 +294,14 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
* attr with val. The next pass should be '=', otherwise we will
* reset it.
*/
+ if (slen > ctx->attr_size) {
+ if (ctx->attr_size == ATTRSIZE) {
+ ctx->attr = slapi_ch_calloc(sizeof(char), slen+1);
+ } else {
+ ctx->attr = slapi_ch_realloc(ctx->attr, sizeof(char) * (slen+1));
+ }
+ ctx->attr_size = slen+1;
+ }
memcpy(ctx->attr, val, slen);
ctx->attr_position = slen;
}
@@ -302,9 +311,20 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
} else {
if (special_attr_char(val[0])) {
/* this is not an attribute, we should not be collecting this, reset everything */
- memset(ctx->attr, '\0', ATTRSIZE);
+ memset(ctx->attr, '\0', ctx->attr_size);
ctx->attr_position = 0;
} else {
+ /* we can be adding char by char and overrun allocated size */
+ if (ctx->attr_position >= ctx->attr_size) {
+ if (ctx->attr_size == ATTRSIZE) {
+ char *ctxattr = slapi_ch_calloc(sizeof(char), ctx->attr_size + ATTRSIZE);
+ memcpy(ctxattr, ctx->attr, ctx->attr_size);
+ ctx->attr = ctxattr;
+ } else {
+ ctx->attr = slapi_ch_realloc(ctx->attr, sizeof(char) * (ctx->attr_size + ATTRSIZE));
+ }
+ ctx->attr_size = ctx->attr_size + ATTRSIZE;
+ }
memcpy(ctx->attr + ctx->attr_position, val, 1);
ctx->attr_position++;
}
@@ -377,7 +397,7 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
ctx->next_arg_needs_esc_norm = 0;
ctx->attr_found = 0;
ctx->attr_position = 0;
- memset(ctx->attr, '\0', ATTRSIZE);
+ memset(ctx->attr, '\0', ctx->attr_size);
slapi_ch_free_string(&buf);

return filter_len;
@@ -416,12 +436,14 @@ slapi_filter_sprintf(const char *fmt, ...)
{
struct filter_ctx ctx = {0};
va_list args;
+ char attr_static[ATTRSIZE] = {0};
char *buf;
int rc;

buf = slapi_ch_calloc(sizeof(char), FILTER_BUF + 1);
ctx.buf = buf;
- memset(ctx.attr, '\0', ATTRSIZE);
+ ctx.attr = attr_static;
+ ctx.attr_size = ATTRSIZE;
ctx.attr_position = 0;
ctx.attr_found = 0;
ctx.buf_len = FILTER_BUF;
@@ -438,6 +460,10 @@ slapi_filter_sprintf(const char *fmt, ...)
}
va_end(args);

+ if (ctx.attr_size > ATTRSIZE) {
+ slapi_ch_free_string(&ctx.attr);
+ }
+
return ctx.buf;
}


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