From 239f8d93866605b05f4e6b551f4327dc7fcb922b Mon Sep 17 00:00:00 2001

From: Viktor Szakats <commit@vsz.me>

Date: Tue, 23 Feb 2021 14:54:46 +0100

Subject: [PATCH 1/2] transfer: strip credentials from the auto-referer header

 field

Added test 2081 to verify.

CVE-2021-22876

Bug: https://curl.se/docs/CVE-2021-22876.html

Upstream-commit: 7214288898f5625a6cc196e22a74232eada7861c

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 lib/transfer.c | 25 +++++++++++++++++++++++--

 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/lib/transfer.c b/lib/transfer.c

index ecd1063..263b178 100644

--- a/lib/transfer.c

+++ b/lib/transfer.c

@@ -1473,6 +1473,7 @@ CURLcode Curl_follow(struct Curl_easy *data,

   /* Location: redirect */

   bool disallowport = FALSE;

   bool reachedmax = FALSE;

+  CURLUcode uc;

   if(type == FOLLOW_REDIR) {

     if((data->set.maxredirs != -1) &&

@@ -1488,6 +1489,9 @@ CURLcode Curl_follow(struct Curl_easy *data,

       data->set.followlocation++; /* count location-followers */

       if(data->set.http_auto_referer) {

+        CURLU *u;

+        char *referer;

+

         /* We are asked to automatically set the previous URL as the referer

            when we get the next URL. We pick the ->url field, which may or may

            not be 100% correct */

@@ -1497,9 +1501,26 @@ CURLcode Curl_follow(struct Curl_easy *data,

           data->change.referer_alloc = FALSE;

         }

-        data->change.referer = strdup(data->change.url);

-        if(!data->change.referer)

+        /* Make a copy of the URL without crenditals and fragment */

+        u = curl_url();

+        if(!u)

+          return CURLE_OUT_OF_MEMORY;

+

+        uc = curl_url_set(u, CURLUPART_URL, data->change.url, 0);

+        if(!uc)

+          uc = curl_url_set(u, CURLUPART_FRAGMENT, NULL, 0);

+        if(!uc)

+          uc = curl_url_set(u, CURLUPART_USER, NULL, 0);

+        if(!uc)

+          uc = curl_url_set(u, CURLUPART_PASSWORD, NULL, 0);

+        if(!uc)

+          uc = curl_url_get(u, CURLUPART_URL, &referer, 0);

+

+        curl_url_cleanup(u);

+

+        if(uc || referer == NULL)

           return CURLE_OUT_OF_MEMORY;

+        data->change.referer = referer;

         data->change.referer_alloc = TRUE; /* yes, free this later */

       }

     }

-- 

2.30.2

From f7d1d478b87499ce31d6aa3251830b78447ad952 Mon Sep 17 00:00:00 2001

From: Daniel Stenberg <daniel@haxx.se>

Date: Mon, 29 Mar 2021 09:32:14 +0200

Subject: [PATCH 2/2] transfer: clear 'referer' in declaration

To silence (false positive) compiler warnings about it.

Follow-up to 7214288898f5625

Reviewed-by: Marcel Raad

Closes #6810

Upstream-commit: 6bb028dbda6cbfe83f66de773544f71e4813160f

Signed-off-by: Kamil Dudka <kdudka@redhat.com>

---

 lib/transfer.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/transfer.c b/lib/transfer.c

index 263b178..ad5a7ba 100644

--- a/lib/transfer.c

+++ b/lib/transfer.c

@@ -1490,7 +1490,7 @@ CURLcode Curl_follow(struct Curl_easy *data,

       if(data->set.http_auto_referer) {

         CURLU *u;

-        char *referer;

+        char *referer = NULL;

         /* We are asked to automatically set the previous URL as the referer

            when we get the next URL. We pick the ->url field, which may or may

@@ -1518,7 +1518,7 @@ CURLcode Curl_follow(struct Curl_easy *data,

         curl_url_cleanup(u);

-        if(uc || referer == NULL)

+        if(uc || !referer)

           return CURLE_OUT_OF_MEMORY;

         data->change.referer = referer;

         data->change.referer_alloc = TRUE; /* yes, free this later */

-- 

2.30.2