Bug 1326307

Summary: qemu: Buffer overflow in mipsnet_ioport_write() function
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED UPSTREAM QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abaron, ailan, alonbl, aortega, apevec, areis, ayoung, bmcclain, chrisw, dallan, dblechte, drjones, eedri, gklein, gkotton, imammedo, jen, jjoyce, jschluet, knoel, lhh, lpeer, markmc, mgoldboi, michal.skrivanek, mkenneth, mrezanin, mst, pbonzini, ppandit, rbalakri, rbryant, rkrcmar, sclewis, security-response-team, sherold, srevivo, tdecacqu, vkuznets, ykaul, ylavi
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-01-12 18:32:23 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 1326310    

Description Adam Mariš 2016-04-12 11:46:29 UTC 
A buffer overflow vulnerability in mipsnet_ioport_write() function was found.

Vulnerable code (hw/net/mipsnet.c):

static void mipsnet_ioport_write(void *opaque, hwaddr addr,
uint64_t val, unsigned int size)
{
MIPSnetState *s = opaque;

addr &= 0x3f;
trace_mipsnet_write(addr, val);
switch (addr) {
case MIPSNET_TX_DATA_COUNT:
s->tx_count = (val <= MAX_ETH_FRAME_SIZE) ? val : 0;// set tx_count=0
s->tx_written = 0;
break;
...
case MIPSNET_TX_DATA_BUFFER:
s->tx_buffer[s->tx_written++] = val;
if (s->tx_written == s->tx_count) { // never get executed, causes the s->tx_buffer to overflow
/* Send buffer. */
trace_mipsnet_send(s->tx_count);
qemu_send_packet(qemu_get_queue(s->nic), s->tx_buffer, s->tx_count);
s->tx_count = s->tx_written = 0;
s->intctl |= MIPSNET_INTCTL_TXDONE;
s->busy = 1;
mipsnet_update_irq(s);
}
...
}

s->tx_written can exceed the MAX_ETH_FRAME_SIZE causing s->tx_buffer to overflow.
Comment 1 Adam Mariš 2016-04-12 11:46:50 UTC 
Acknowledgments:

Name: Li Qiang (Qihoo 360 Inc.)