- bsc#963783 - VUL-1: CVE-2016-1981: xen: net: e1000 infinite loop
in start_xmit and e1000_receive_iov routines CVE-2016-1981-qemuu-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch CVE-2016-1981-qemut-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch OBS-URL: https://build.opensuse.org/package/show/Virtualization/xen?expand=0&rev=396
This commit is contained in:
Charles Arnold
Git OBS Bridge
parent
39134eb9d2
commit
fbfd58d3a2
@ -0,0 +1,94 @@
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The start_xmit() and e1000_receive_iov() functions implement DMA transfers
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iterating over a set of descriptors that the guest's e1000 driver
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prepares:
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- the TDLEN and RDLEN registers store the total size of the descriptor
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area,
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- while the TDH and RDH registers store the offset (in whole tx / rx
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descriptors) into the area where the transfer is supposed to start.
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Each time a descriptor is processed, the TDH and RDH register is bumped
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(as appropriate for the transfer direction).
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QEMU already contains logic to deal with bogus transfers submitted by the
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guest:
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- Normally, the transmit case wants to increase TDH from its initial value
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to TDT. (TDT is allowed to be numerically smaller than the initial TDH
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value; wrapping at or above TDLEN bytes to zero is normal.) The failsafe
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that QEMU currently has here is a check against reaching the original
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TDH value again -- a complete wraparound, which should never happen.
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- In the receive case RDH is increased from its initial value until
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"total_size" bytes have been received; preferably in a single step, or
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in "s->rxbuf_size" byte steps, if the latter is smaller. However, null
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RX descriptors are skipped without receiving data, while RDH is
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incremented just the same. QEMU tries to prevent an infinite loop
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(processing only null RX descriptors) by detecting whether RDH assumes
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its original value during the loop. (Again, wrapping from RDLEN to 0 is
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normal.)
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What both directions miss is that the guest could program TDLEN and RDLEN
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so low, and the initial TDH and RDH so high, that these registers will
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immediately be truncated to zero, and then never reassume their initial
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values in the loop -- a full wraparound will never occur.
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The condition that expresses this is:
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xdh_start >= s->mac_reg[XDLEN] / sizeof(desc)
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i.e., TDH or RDH start out after the last whole rx or tx descriptor that
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fits into the TDLEN or RDLEN sized area.
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This condition could be checked before we enter the loops, but
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pci_dma_read() / pci_dma_write() knows how to fill in buffers safely for
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bogus DMA addresses, so we just extend the existing failsafes with the
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above condition.
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Cc: "Michael S. Tsirkin" <address@hidden>
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Cc: Petr Matousek <address@hidden>
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Cc: Stefano Stabellini <address@hidden>
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Cc: Prasad Pandit <address@hidden>
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Cc: Michael Roth <address@hidden>
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Cc: Jason Wang <address@hidden>
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RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1296044
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Signed-off-by: Laszlo Ersek <address@hidden>
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Reviewed-by: Jason Wang <address@hidden>
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---
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Notes:
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Regarding the public posting: we made an honest effort to vet this
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vulnerability, and the impact seems low -- no host side reads/writes,
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"just" a DoS (infinite loop). We decided the patch could be posted
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publicly, for the usual review process. Jason and Prasad checked the
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patch in the internal discussion already, but comments, improvements
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etc. are clearly welcome. The CVE request is underway. Thanks.
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hw/net/e1000.c | 6 ++++--
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1 file changed, 4 insertions(+), 2 deletions(-)
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Index: xen-4.6.0-testing/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
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===================================================================
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--- xen-4.6.0-testing.orig/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
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+++ xen-4.6.0-testing/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
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@@ -537,7 +537,8 @@ start_xmit(E1000State *s)
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* bogus values to TDT/TDLEN.
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* there's nothing too intelligent we could do about this.
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*/
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- if (s->mac_reg[TDH] == tdh_start) {
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+ if (s->mac_reg[TDH] == tdh_start ||
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+ tdh_start >= s->mac_reg[TDLEN] / sizeof(desc)) {
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DBGOUT(TXERR, "TDH wraparound @%x, TDT %x, TDLEN %x\n",
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tdh_start, s->mac_reg[TDT], s->mac_reg[TDLEN]);
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break;
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@@ -727,7 +728,8 @@ e1000_receive(void *opaque, const uint8_
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s->mac_reg[RDH] = 0;
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s->check_rxov = 1;
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/* see comment in start_xmit; same here */
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- if (s->mac_reg[RDH] == rdh_start) {
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+ if (s->mac_reg[RDH] == rdh_start ||
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+ rdh_start >= s->mac_reg[RDLEN] / sizeof(desc)) {
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DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
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rdh_start, s->mac_reg[RDT], s->mac_reg[RDLEN]);
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set_ics(s, 0, E1000_ICS_RXO);
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@ -0,0 +1,94 @@
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The start_xmit() and e1000_receive_iov() functions implement DMA transfers
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iterating over a set of descriptors that the guest's e1000 driver
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prepares:
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- the TDLEN and RDLEN registers store the total size of the descriptor
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area,
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- while the TDH and RDH registers store the offset (in whole tx / rx
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descriptors) into the area where the transfer is supposed to start.
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Each time a descriptor is processed, the TDH and RDH register is bumped
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(as appropriate for the transfer direction).
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QEMU already contains logic to deal with bogus transfers submitted by the
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guest:
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- Normally, the transmit case wants to increase TDH from its initial value
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to TDT. (TDT is allowed to be numerically smaller than the initial TDH
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value; wrapping at or above TDLEN bytes to zero is normal.) The failsafe
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that QEMU currently has here is a check against reaching the original
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TDH value again -- a complete wraparound, which should never happen.
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- In the receive case RDH is increased from its initial value until
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"total_size" bytes have been received; preferably in a single step, or
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in "s->rxbuf_size" byte steps, if the latter is smaller. However, null
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RX descriptors are skipped without receiving data, while RDH is
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incremented just the same. QEMU tries to prevent an infinite loop
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(processing only null RX descriptors) by detecting whether RDH assumes
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its original value during the loop. (Again, wrapping from RDLEN to 0 is
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normal.)
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What both directions miss is that the guest could program TDLEN and RDLEN
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so low, and the initial TDH and RDH so high, that these registers will
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immediately be truncated to zero, and then never reassume their initial
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values in the loop -- a full wraparound will never occur.
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The condition that expresses this is:
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xdh_start >= s->mac_reg[XDLEN] / sizeof(desc)
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i.e., TDH or RDH start out after the last whole rx or tx descriptor that
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fits into the TDLEN or RDLEN sized area.
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This condition could be checked before we enter the loops, but
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pci_dma_read() / pci_dma_write() knows how to fill in buffers safely for
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bogus DMA addresses, so we just extend the existing failsafes with the
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above condition.
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Cc: "Michael S. Tsirkin" <address@hidden>
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Cc: Petr Matousek <address@hidden>
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Cc: Stefano Stabellini <address@hidden>
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Cc: Prasad Pandit <address@hidden>
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Cc: Michael Roth <address@hidden>
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Cc: Jason Wang <address@hidden>
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RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1296044
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Signed-off-by: Laszlo Ersek <address@hidden>
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Reviewed-by: Jason Wang <address@hidden>
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---
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Notes:
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Regarding the public posting: we made an honest effort to vet this
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vulnerability, and the impact seems low -- no host side reads/writes,
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"just" a DoS (infinite loop). We decided the patch could be posted
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publicly, for the usual review process. Jason and Prasad checked the
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patch in the internal discussion already, but comments, improvements
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etc. are clearly welcome. The CVE request is underway. Thanks.
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hw/net/e1000.c | 6 ++++--
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1 file changed, 4 insertions(+), 2 deletions(-)
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Index: xen-4.6.0-testing/tools/qemu-xen-dir-remote/hw/net/e1000.c
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===================================================================
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--- xen-4.6.0-testing.orig/tools/qemu-xen-dir-remote/hw/net/e1000.c
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+++ xen-4.6.0-testing/tools/qemu-xen-dir-remote/hw/net/e1000.c
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@@ -815,7 +815,8 @@ start_xmit(E1000State *s)
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* bogus values to TDT/TDLEN.
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* there's nothing too intelligent we could do about this.
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*/
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- if (s->mac_reg[TDH] == tdh_start) {
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+ if (s->mac_reg[TDH] == tdh_start ||
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+ tdh_start >= s->mac_reg[TDLEN] / sizeof(desc)) {
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DBGOUT(TXERR, "TDH wraparound @%x, TDT %x, TDLEN %x\n",
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tdh_start, s->mac_reg[TDT], s->mac_reg[TDLEN]);
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break;
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@@ -1059,7 +1060,8 @@ e1000_receive_iov(NetClientState *nc, co
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if (++s->mac_reg[RDH] * sizeof(desc) >= s->mac_reg[RDLEN])
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s->mac_reg[RDH] = 0;
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/* see comment in start_xmit; same here */
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- if (s->mac_reg[RDH] == rdh_start) {
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+ if (s->mac_reg[RDH] == rdh_start ||
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+ rdh_start >= s->mac_reg[RDLEN] / sizeof(desc)) {
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DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
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rdh_start, s->mac_reg[RDT], s->mac_reg[RDLEN]);
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set_ics(s, 0, E1000_ICS_RXO);
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@ -1,3 +1,11 @@
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-------------------------------------------------------------------
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Wed Jan 27 08:23:26 MST 2016 - carnold@suse.com
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- bsc#963783 - VUL-1: CVE-2016-1981: xen: net: e1000 infinite loop
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in start_xmit and e1000_receive_iov routines
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CVE-2016-1981-qemuu-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch
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CVE-2016-1981-qemut-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch
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-------------------------------------------------------------------
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Wed Jan 20 08:21:42 MST 2016 - carnold@suse.com
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7
xen.spec
7
xen.spec
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#
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# spec file for package xen
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#
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# Copyright (c) 2016 SUSE LINUX GmbH, Nuernberg, Germany.
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# Copyright (c) 2016 SUSE LINUX Products GmbH, Nuernberg, Germany.
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#
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# All modifications and additions to the file contributed by third parties
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# remain the property of their copyright owners, unless otherwise agreed
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@ -15,7 +15,6 @@
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# Please submit bugfixes or comments via http://bugs.opensuse.org/
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#
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# needssslcertforbuild
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Name: xen
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@ -277,6 +276,8 @@ Patch281: CVE-2013-4537-qemut-ssi-sd-fix-buffer-overrun-on-invalid-state-l
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Patch282: CVE-2015-1779-qemuu-incrementally-decode-websocket-frames.patch
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Patch283: CVE-2015-1779-qemuu-limit-size-of-HTTP-headers-from-websockets-clients.patch
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Patch284: CVE-2013-4539-qemut-tsc210x-fix-buffer-overrun-on-invalid-state-load.patch
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Patch285: CVE-2016-1981-qemuu-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch
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Patch286: CVE-2016-1981-qemut-e1000-eliminate-infinite-loops-on-out-of-bounds-transfer.patch
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# Our platform specific patches
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Patch321: xen-destdir.patch
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Patch322: vif-bridge-no-iptables.patch
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@ -620,6 +621,8 @@ Authors:
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%patch282 -p1
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%patch283 -p1
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%patch284 -p1
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%patch285 -p1
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%patch286 -p1
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# Our platform specific patches
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%patch321 -p1
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%patch322 -p1
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