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From 22b3d1cf0216f4369f01678c587da265c2e465af Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Sat, 28 Nov 2020 00:27:21 +0100
Subject: [PATCH] ftp: make wc_statemach loop instead of recurse
CVE-2020-8285
Fixes #6255
Bug: https://curl.se/docs/CVE-2020-8285.html
Reported-by: xnynx on github
Upstream-commit: 69a358f2186e04cf44698b5100332cbf1ee7f01d
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
lib/ftp.c | 204 +++++++++++++++++++++++++++---------------------------
1 file changed, 103 insertions(+), 101 deletions(-)
diff --git a/lib/ftp.c b/lib/ftp.c
index 7dbf080..482ab3a 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -3786,130 +3786,132 @@ static CURLcode init_wc_data(struct connectdata *conn)
return result;
}
-/* This is called recursively */
static CURLcode wc_statemach(struct connectdata *conn)
{
struct WildcardData * const wildcard = &(conn->data->wildcard);
CURLcode result = CURLE_OK;
- switch(wildcard->state) {
- case CURLWC_INIT:
- result = init_wc_data(conn);
- if(wildcard->state == CURLWC_CLEAN)
- /* only listing! */
- break;
- wildcard->state = result ? CURLWC_ERROR : CURLWC_MATCHING;
- break;
+ for(;;) {
+ switch(wildcard->state) {
+ case CURLWC_INIT:
+ result = init_wc_data(conn);
+ if(wildcard->state == CURLWC_CLEAN)
+ /* only listing! */
+ return result;
+ wildcard->state = result ? CURLWC_ERROR : CURLWC_MATCHING;
+ return result;
- case CURLWC_MATCHING: {
- /* In this state is LIST response successfully parsed, so lets restore
- previous WRITEFUNCTION callback and WRITEDATA pointer */
- struct ftp_wc *ftpwc = wildcard->protdata;
- conn->data->set.fwrite_func = ftpwc->backup.write_function;
- conn->data->set.out = ftpwc->backup.file_descriptor;
- ftpwc->backup.write_function = ZERO_NULL;
- ftpwc->backup.file_descriptor = NULL;
- wildcard->state = CURLWC_DOWNLOADING;
-
- if(Curl_ftp_parselist_geterror(ftpwc->parser)) {
- /* error found in LIST parsing */
- wildcard->state = CURLWC_CLEAN;
- return wc_statemach(conn);
- }
- if(wildcard->filelist.size == 0) {
- /* no corresponding file */
- wildcard->state = CURLWC_CLEAN;
- return CURLE_REMOTE_FILE_NOT_FOUND;
+ case CURLWC_MATCHING: {
+ /* In this state is LIST response successfully parsed, so lets restore
+ previous WRITEFUNCTION callback and WRITEDATA pointer */
+ struct ftp_wc *ftpwc = wildcard->protdata;
+ conn->data->set.fwrite_func = ftpwc->backup.write_function;
+ conn->data->set.out = ftpwc->backup.file_descriptor;
+ ftpwc->backup.write_function = ZERO_NULL;
+ ftpwc->backup.file_descriptor = NULL;
+ wildcard->state = CURLWC_DOWNLOADING;
+
+ if(Curl_ftp_parselist_geterror(ftpwc->parser)) {
+ /* error found in LIST parsing */
+ wildcard->state = CURLWC_CLEAN;
+ continue;
+ }
+ if(wildcard->filelist.size == 0) {
+ /* no corresponding file */
+ wildcard->state = CURLWC_CLEAN;
+ return CURLE_REMOTE_FILE_NOT_FOUND;
+ }
+ continue;
}
- return wc_statemach(conn);
- }
- case CURLWC_DOWNLOADING: {
- /* filelist has at least one file, lets get first one */
- struct ftp_conn *ftpc = &conn->proto.ftpc;
- struct curl_fileinfo *finfo = wildcard->filelist.head->ptr;
+ case CURLWC_DOWNLOADING: {
+ /* filelist has at least one file, lets get first one */
+ struct ftp_conn *ftpc = &conn->proto.ftpc;
+ struct curl_fileinfo *finfo = wildcard->filelist.head->ptr;
- char *tmp_path = aprintf("%s%s", wildcard->path, finfo->filename);
- if(!tmp_path)
- return CURLE_OUT_OF_MEMORY;
+ char *tmp_path = aprintf("%s%s", wildcard->path, finfo->filename);
+ if(!tmp_path)
+ return CURLE_OUT_OF_MEMORY;
- /* switch default "state.pathbuffer" and tmp_path, good to see
- ftp_parse_url_path function to understand this trick */
- Curl_safefree(conn->data->state.pathbuffer);
- conn->data->state.pathbuffer = tmp_path;
- conn->data->state.path = tmp_path;
-
- infof(conn->data, "Wildcard - START of \"%s\"\n", finfo->filename);
- if(conn->data->set.chunk_bgn) {
- long userresponse;
- Curl_set_in_callback(conn->data, true);
- userresponse = conn->data->set.chunk_bgn(
- finfo, wildcard->customptr, (int)wildcard->filelist.size);
- Curl_set_in_callback(conn->data, false);
- switch(userresponse) {
- case CURL_CHUNK_BGN_FUNC_SKIP:
- infof(conn->data, "Wildcard - \"%s\" skipped by user\n",
- finfo->filename);
- wildcard->state = CURLWC_SKIP;
- return wc_statemach(conn);
- case CURL_CHUNK_BGN_FUNC_FAIL:
- return CURLE_CHUNK_FAILED;
+ /* switch default "state.pathbuffer" and tmp_path, good to see
+ ftp_parse_url_path function to understand this trick */
+ Curl_safefree(conn->data->state.pathbuffer);
+ conn->data->state.pathbuffer = tmp_path;
+ conn->data->state.path = tmp_path;
+
+ infof(conn->data, "Wildcard - START of \"%s\"\n", finfo->filename);
+ if(conn->data->set.chunk_bgn) {
+ long userresponse;
+ Curl_set_in_callback(conn->data, true);
+ userresponse = conn->data->set.chunk_bgn(
+ finfo, wildcard->customptr, (int)wildcard->filelist.size);
+ Curl_set_in_callback(conn->data, false);
+ switch(userresponse) {
+ case CURL_CHUNK_BGN_FUNC_SKIP:
+ infof(conn->data, "Wildcard - \"%s\" skipped by user\n",
+ finfo->filename);
+ wildcard->state = CURLWC_SKIP;
+ continue;
+ case CURL_CHUNK_BGN_FUNC_FAIL:
+ return CURLE_CHUNK_FAILED;
+ }
}
- }
- if(finfo->filetype != CURLFILETYPE_FILE) {
- wildcard->state = CURLWC_SKIP;
- return wc_statemach(conn);
- }
+ if(finfo->filetype != CURLFILETYPE_FILE) {
+ wildcard->state = CURLWC_SKIP;
+ continue;
+ }
- if(finfo->flags & CURLFINFOFLAG_KNOWN_SIZE)
- ftpc->known_filesize = finfo->size;
+ if(finfo->flags & CURLFINFOFLAG_KNOWN_SIZE)
+ ftpc->known_filesize = finfo->size;
- result = ftp_parse_url_path(conn);
- if(result)
- return result;
+ result = ftp_parse_url_path(conn);
+ if(result)
+ return result;
- /* we don't need the Curl_fileinfo of first file anymore */
- Curl_llist_remove(&wildcard->filelist, wildcard->filelist.head, NULL);
+ /* we don't need the Curl_fileinfo of first file anymore */
+ Curl_llist_remove(&wildcard->filelist, wildcard->filelist.head, NULL);
- if(wildcard->filelist.size == 0) { /* remains only one file to down. */
- wildcard->state = CURLWC_CLEAN;
- /* after that will be ftp_do called once again and no transfer
- will be done because of CURLWC_CLEAN state */
- return CURLE_OK;
+ if(wildcard->filelist.size == 0) { /* remains only one file to down. */
+ wildcard->state = CURLWC_CLEAN;
+ /* after that will be ftp_do called once again and no transfer
+ will be done because of CURLWC_CLEAN state */
+ return CURLE_OK;
+ }
+ return result;
}
- } break;
- case CURLWC_SKIP: {
- if(conn->data->set.chunk_end) {
- Curl_set_in_callback(conn->data, true);
- conn->data->set.chunk_end(conn->data->wildcard.customptr);
- Curl_set_in_callback(conn->data, false);
+ case CURLWC_SKIP: {
+ if(conn->data->set.chunk_end) {
+ Curl_set_in_callback(conn->data, true);
+ conn->data->set.chunk_end(conn->data->wildcard.customptr);
+ Curl_set_in_callback(conn->data, false);
+ }
+ Curl_llist_remove(&wildcard->filelist, wildcard->filelist.head, NULL);
+ wildcard->state = (wildcard->filelist.size == 0) ?
+ CURLWC_CLEAN : CURLWC_DOWNLOADING;
+ continue;
}
- Curl_llist_remove(&wildcard->filelist, wildcard->filelist.head, NULL);
- wildcard->state = (wildcard->filelist.size == 0) ?
- CURLWC_CLEAN : CURLWC_DOWNLOADING;
- return wc_statemach(conn);
- }
- case CURLWC_CLEAN: {
- struct ftp_wc *ftpwc = wildcard->protdata;
- result = CURLE_OK;
- if(ftpwc)
- result = Curl_ftp_parselist_geterror(ftpwc->parser);
+ case CURLWC_CLEAN: {
+ struct ftp_wc *ftpwc = wildcard->protdata;
+ result = CURLE_OK;
+ if(ftpwc)
+ result = Curl_ftp_parselist_geterror(ftpwc->parser);
- wildcard->state = result ? CURLWC_ERROR : CURLWC_DONE;
- } break;
+ wildcard->state = result ? CURLWC_ERROR : CURLWC_DONE;
+ return result;
+ }
- case CURLWC_DONE:
- case CURLWC_ERROR:
- case CURLWC_CLEAR:
- if(wildcard->dtor)
- wildcard->dtor(wildcard->protdata);
- break;
+ case CURLWC_DONE:
+ case CURLWC_ERROR:
+ case CURLWC_CLEAR:
+ if(wildcard->dtor)
+ wildcard->dtor(wildcard->protdata);
+ return result;
+ }
}
-
- return result;
+ /* UNREACHABLE */
}
/***********************************************************************
--
2.26.2
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