Blame SOURCES/0086-CVE-2017-15134-389-ds-base-Remote-DoS-via-search-fil.patch

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From 040c492b4beb0efcd34b8420f682187441767055 Mon Sep 17 00:00:00 2001
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From: Mark Reynolds <mreynolds@redhat.com>
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Date: Tue, 16 Jan 2018 09:46:49 -0500
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Subject: [PATCH] CVE-2017-15134 389-ds-base: Remote DoS via search filters in
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 slapi_filter_sprintf
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Description: Improper handling of a search filter in slapi_filter_sprintf
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             in slapd/util.c can lead to remote server crash and denial
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             of service.
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https://bugzilla.redhat.com/show_bug.cgi?id=1529117
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---
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 ldap/servers/slapd/util.c | 36 +++++++++++++++++++++++++++++++-----
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 1 file changed, 31 insertions(+), 5 deletions(-)
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diff --git a/ldap/servers/slapd/util.c b/ldap/servers/slapd/util.c
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index 4ff6d4141..ffeeff6f3 100644
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--- a/ldap/servers/slapd/util.c
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+++ b/ldap/servers/slapd/util.c
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@@ -224,9 +224,10 @@ escape_string_for_filename(const char *str, char buf[BUFSIZ])
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 struct filter_ctx {
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   char *buf;
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-  char attr[ATTRSIZE];
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+  char *attr;
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   int attr_position;
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   int attr_found;
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+  size_t attr_size;
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   int buf_size;
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   int buf_len;
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   int next_arg_needs_esc_norm;
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@@ -265,7 +266,7 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
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      *  Start collecting the attribute name so we can use the correct
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      *  syntax normalization func.
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      */
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-    if(ctx->attr_found == 0 && ctx->attr_position < (ATTRSIZE - 1)){
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+    if(ctx->attr_found == 0 && ctx->attr_position < (ctx->attr_size - 1)) {
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         if(ctx->attr[0] == '\0'){
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             if(strstr(val,"=")){
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                 /* we have an attr we need to record */
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@@ -279,6 +280,14 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
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                  *  attr with val.  The next pass should be '=', otherwise we will
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                  *  reset it.
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                  */
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+                if (slen > ctx->attr_size) {
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+                    if (ctx->attr_size == ATTRSIZE) {
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+                        ctx->attr = slapi_ch_calloc(sizeof(char), slen+1);
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+                    } else {
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+                        ctx->attr = slapi_ch_realloc(ctx->attr, sizeof(char) * (slen+1));
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+                    }
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+                    ctx->attr_size = slen+1;
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+                }
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                 memcpy(ctx->attr, val, slen);
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                 ctx->attr_position = slen;
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             }
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@@ -288,9 +297,20 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
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             } else {
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                 if(special_attr_char(val[0])){
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                     /* this is not an attribute, we should not be collecting this, reset everything */
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-                    memset(ctx->attr, '\0', ATTRSIZE);
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+                    memset(ctx->attr, '\0', ctx->attr_size);
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                     ctx->attr_position = 0;
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                 } else {
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+                    /* we can be adding char by char and overrun allocated size */
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+                    if (ctx->attr_position >= ctx->attr_size) {
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+                        if (ctx->attr_size == ATTRSIZE) {
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+                            char *ctxattr = slapi_ch_calloc(sizeof(char), ctx->attr_size + ATTRSIZE);
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+                            memcpy(ctxattr, ctx->attr, ctx->attr_size);
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+                            ctx->attr = ctxattr;
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+                        } else {
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+                            ctx->attr = slapi_ch_realloc(ctx->attr, sizeof(char) * (ctx->attr_size + ATTRSIZE));
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+                        }
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+                        ctx->attr_size = ctx->attr_size + ATTRSIZE;
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+                    }
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                     memcpy(ctx->attr + ctx->attr_position, val, 1);
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                     ctx->attr_position++;
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                 }
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@@ -363,7 +383,7 @@ filter_stuff_func(void *arg, const char *val, PRUint32 slen)
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         ctx->next_arg_needs_esc_norm = 0;
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         ctx->attr_found = 0;
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         ctx->attr_position = 0;
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-        memset(ctx->attr, '\0', ATTRSIZE);
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+        memset(ctx->attr, '\0', ctx->attr_size);
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         slapi_ch_free_string(&buf;;
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         return filter_len;
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@@ -402,13 +422,15 @@ slapi_filter_sprintf(const char *fmt, ...)
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 {
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     struct filter_ctx ctx = {0};
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     va_list args;
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+    char attr_static[ATTRSIZE] = {0};
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     char *buf;
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     int rc;
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     buf = slapi_ch_calloc(sizeof(char), FILTER_BUF + 1);
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     ctx.buf = buf;
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-    memset(ctx.attr,'\0', ATTRSIZE);
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     ctx.attr_position = 0;
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+    ctx.attr = attr_static;
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+    ctx.attr_size = ATTRSIZE;
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     ctx.attr_found = 0;
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     ctx.buf_len = FILTER_BUF;
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     ctx.buf_size = 0;
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@@ -424,6 +446,10 @@ slapi_filter_sprintf(const char *fmt, ...)
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     }
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     va_end(args);
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+    if (ctx.attr_size > ATTRSIZE) {
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+        slapi_ch_free_string(&ctx.attr);
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+    }
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+
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     return ctx.buf;
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 }
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-- 
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2.13.6
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