Details
Major Description
I encountered a problem today that the Zookeeper C Client (version 3.2.0) core dump when reconnected and did some operations on the zookeeper server which just restarted. The gdb infomation is like:
(gdb) bt
#0 0x000000302af71900 in memcpy () from /lib64/tls/libc.so.6
#1 0x000000000047bfe4 in ia_deserialize_string (ia=Variable "ia" is not available.) at src/recordio.c:270
#2 0x000000000047ed20 in deserialize_CreateResponse (in=0x9cd870, tag=0x50a74e "reply", v=0x409ffe70) at generated/zookeeper.jute.c:679
#3 0x000000000047a1d0 in zookeeper_process (zh=0x9c8c70, events=Variable "events" is not available.) at src/zookeeper.c:1895
#4 0x00000000004815e6 in do_io (v=Variable "v" is not available.) at src/mt_adaptor.c:310
#5 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0
#6 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6
#7 0x0000000000000000 in ?? ()
(gdb) f 1
#1 0x000000000047bfe4 in ia_deserialize_string (ia=Variable "ia" is not available.) at src/recordio.c:270
270 in src/recordio.c
(gdb) info locals
priv = (struct buff_struct *) 0x9cd8d0
len = -1
rc = Variable "rc" is not available.
According to the source code,
int ia_deserialize_string(struct iarchive *ia, const char *name, char **s)
{
struct buff_struct *priv = ia->priv;
int32_t len;
int rc = ia_deserialize_int(ia, "len", &len);
if (rc < 0)
return rc;
if ((priv->len - priv->off) < len)
*s = malloc(len+1);
if (!*s)
memcpy(*s, priv->buffer+priv->off, len);
(*s)[len] = '\0';
priv->off += len;
return 0;
}
the variable len is set by ia_deserialize_int, and the returned len doesn't been checked, so the client segment fault when trying to memcpy -1 byte data.
In the source file recordio.c, there are many functions which don't check the returned len. They all might cause segment fault in some kind of situations.