Hi Dan,
I had a question about 703ba7fe5e08: "staging: zcache: rename ramster
to zcache" from Jan 18, 2013.
We call ramster_remote_put_handler() from r2net_process_message() like
this:
drivers/staging/zcache/ramster/tcp.c
1320 if (be16_to_cpu(hdr->data_len) > nmh->nh_max_len)
1321 syserr = R2NET_ERR_OVERFLOW;
1322
1323 if (syserr != R2NET_ERR_NONE) {
1324 pr_err("ramster_r2net, message length problem\n");
1325 goto out_respond;
1326 }
1327
1328 r2net_set_func_start_time(sc);
1329 sc->sc_msg_key = be32_to_cpu(hdr->key);
1330 sc->sc_msg_type = be16_to_cpu(hdr->msg_type);
1331 handler_status = (nmh->nh_func)(hdr, sizeof(struct r2net_msg) +
1332 be16_to_cpu(hdr->data_len),
1333 nmh->nh_func_data, &ret_data);
"len" here is "sizeof(struct r2net_msg) + be16_to_cpu(hdr->data_len)",
in other words it's a number from 24-65559.
drivers/staging/zcache/ramster/r2net.c
110 int ramster_remote_put_handler(struct r2net_msg *msg,
111 u32 len, void *data, void **ret_data)
112 {
113 struct tmem_xhandle *xh;
114 char *p = (char *)msg->buf;
115 int datalen = len - sizeof(struct r2net_msg) -
116 sizeof(struct tmem_xhandle);
If len is 24 then we're setting "datalen" to a negative number. I
followed the code and I think there is a path where a negative here
might trigger a BUG_ON().
117 u16 msgtype = be16_to_cpu(msg->msg_type);
118 bool ephemeral = (msgtype == RMSTR_TMEM_PUT_EPH);
119 unsigned long flags;
120 int ret;
121
122 xh = (struct tmem_xhandle *)p;
123 p += sizeof(struct tmem_xhandle);
124 zcache_autocreate_pool(xh->client_id, xh->pool_id, ephemeral);
125 local_irq_save(flags);
126 ret = zcache_put_page(xh->client_id, xh->pool_id, &xh->oid,
xh->index,
127 p, datalen, true, ephemeral);
128 local_irq_restore(flags);
129 return ret;
130 }
regards,
dan carpenter
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