Re: [Libguestfs] [nbdkit PATCH v2 5/7] server: Allow longer NBD_OPT

On 9/28/19 4:38 PM, Richard W.M. Jones wrote: >On Fri, Sep 27, 2019 at 11:48:47PM -0500, Eric Blake wrote: >>Fixes the fact that clients could not request the maximum string >>length except with NBD_OPT_EXPORT_LEN. Updates the testsuite to >>match. >> >>Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; >>--- >>@@ -255,7 +255,7 @@ negotiate_handshake_newstyle_options (struct connection *conn) >> uint64_t version; >> uint32_t option; >> uint32_t optlen; >>- char data[MAX_OPTION_LENGTH+1]; >>+ CLEANUP_FREE char *data = NULL; > >Even though you have the CLEANUP here ... Scope is too wide. I need to sink the declaration... > >> struct nbd_export_name_option_reply handshake_finish; >> const char *optname; >> uint64_t exportsize; >>@@ -281,6 +281,11 @@ negotiate_handshake_newstyle_options (struct connection *conn) >> nbdkit_error ("client option data too long (%" PRIu32 ")", optlen); >> return -1; >> } >>+ data = malloc (optlen + 1); /* Allowing a trailing NUL helps some uses */ >>+ if (data == NULL) { >>+ nbdkit_error ("malloc: %m"); >>+ return -1; >>+ } ...inside the while loop, so that each iteration of the loop frees and reallocates a data buffer. > >... when I run this patch series under valgrind I get mainly errors >originating at this malloc: > >==1251605== 58 bytes in 4 blocks are definitely lost in loss record 4 of 10 >==1251605== at 0x896180B: malloc (vg_replace_malloc.c:309) >==1251605== by 0x11909F: protocol_handshake_newstyle (protocol-handshake-news >tyle.c:288) >==1251605== by 0x118804: protocol_handshake (protocol-handshake.c:55) >==1251605== by 0x112080: handle_single_connection (connections.c:165) >==1251605== by 0x11B84D: start_thread (sockets.c:276) >==1251605== by 0x8BB74E1: start_thread (pthread_create.c:479) >==1251605== by 0x8CD3642: clone (clone.S:95) > >I didn't look at it closely but there does appear to be a memory leak >in this patch. Yep, and you pointed it out very nicely. I'll fix before pushing.