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file: reject paths using embedded %00

Mostly because we use C strings and they end at a binary zero so we know
we can't open a file name using an embedded binary zero.

Reported-by: research@g0blin.co.uk
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bagder committed Sep 25, 2014
1 parent 46d71e7 commit 53cbea22310f1509e98f5537ef3a83c6e600629f
Showing with 10 additions and 2 deletions.
  1. +10 −2 lib/file.c
@@ -196,8 +196,9 @@ static CURLcode file_connect(struct connectdata *conn, bool *done)
int i;
char *actual_path;
#endif
int real_path_len;

real_path = curl_easy_unescape(data, data->state.path, 0, NULL);
real_path = curl_easy_unescape(data, data->state.path, 0, &real_path_len);
if(!real_path)
return CURLE_OUT_OF_MEMORY;

@@ -222,16 +223,23 @@ static CURLcode file_connect(struct connectdata *conn, bool *done)
(actual_path[2] == ':' || actual_path[2] == '|')) {
actual_path[2] = ':';
actual_path++;
real_path_len--;
}

/* change path separators from '/' to '\\' for DOS, Windows and OS/2 */
for(i=0; actual_path[i] != '\0'; ++i)
for(i=0; i < real_path_len; ++i)
if(actual_path[i] == '/')
actual_path[i] = '\\';
else if(!actual_path[i]) /* binary zero */
return CURLE_URL_MALFORMAT;

fd = open_readonly(actual_path, O_RDONLY|O_BINARY);
file->path = actual_path;
#else
if(memchr(real_path, 0, real_path_len))
/* binary zeroes indicate foul play */
return CURLE_URL_MALFORMAT;

fd = open_readonly(real_path, O_RDONLY);
file->path = real_path;
#endif

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