wget: check chunk length for overflowing off_t

function                                             old     new   delta
retrieve_file_data                                   428     465     +37
wget_main                                           2386    2389      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 40/0)               Total: 40 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/networking/wget.c b/networking/wget.c
index c9e576e69..2650b5384 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -801,7 +801,7 @@ static FILE* prepare_ftp_session(FILE **dfpp, struct host_info *target, len_and_
         if (ftpcmd("SIZE ", target->path, sfp) == 213) {
                 G.content_len = BB_STRTOOFF(G.wget_buf + 4, NULL, 10);
                 if (G.content_len < 0 || errno) {
-                        bb_error_msg_and_die("SIZE value is garbage");
+                        bb_error_msg_and_die("bad SIZE value '%s'", G.wget_buf + 4);
                 }
                 G.got_clen = 1;
         }
@@ -965,11 +965,19 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
                 if (!G.chunked)
                         break;
 
-                fgets_trim_sanitize(dfp, NULL); /* Eat empty line */
+                /* Each chunk ends with "\r\n" - eat it */
+                fgets_trim_sanitize(dfp, NULL);
  get_clen:
+                /* chunk size format is "HEXNUM[;name[=val]]\r\n" */
                 fgets_trim_sanitize(dfp, NULL);
+                errno = 0;
                 G.content_len = STRTOOFF(G.wget_buf, NULL, 16);
-                /* FIXME: error check? */
+                /*
+                 * Had a bug with inputs like "ffffffff0001f400"
+                 * smashing the heap later. Ensure >= 0.
+                 */
+                if (G.content_len < 0 || errno)
+                        bb_error_msg_and_die("bad chunk length '%s'", G.wget_buf);
                 if (G.content_len == 0)
                         break; /* all done! */
                 G.got_clen = 1;