From e273abe9cfa879ad33d14986f7fdeeaeb601d4da Mon Sep 17 00:00:00 2001 From: Mario Preksavec Date: Sun, 3 Jun 2018 17:14:09 +0200 Subject: system/xen: XSA 263 update. Signed-off-by: Mario Preksavec --- system/xen/xsa/xsa262-4.10.patch | 76 ---------------------------------------- 1 file changed, 76 deletions(-) delete mode 100644 system/xen/xsa/xsa262-4.10.patch (limited to 'system/xen/xsa/xsa262-4.10.patch') diff --git a/system/xen/xsa/xsa262-4.10.patch b/system/xen/xsa/xsa262-4.10.patch deleted file mode 100644 index ba9a8ffa22..0000000000 --- a/system/xen/xsa/xsa262-4.10.patch +++ /dev/null @@ -1,76 +0,0 @@ -From: Jan Beulich -Subject: x86/HVM: guard against emulator driving ioreq state in weird ways - -In the case where hvm_wait_for_io() calls wait_on_xen_event_channel(), -p->state ends up being read twice in succession: once to determine that -state != p->state, and then again at the top of the loop. This gives a -compromised emulator a chance to change the state back between the two -reads, potentially keeping Xen in a loop indefinitely. - -Instead: -* Read p->state once in each of the wait_on_xen_event_channel() tests, -* re-use that value the next time around, -* and insist that the states continue to transition "forward" (with the - exception of the transition to STATE_IOREQ_NONE). - -This is XSA-262. - -Signed-off-by: Jan Beulich -Reviewed-by: George Dunlap - ---- a/xen/arch/x86/hvm/ioreq.c -+++ b/xen/arch/x86/hvm/ioreq.c -@@ -87,14 +87,17 @@ static void hvm_io_assist(struct hvm_ior - - static bool hvm_wait_for_io(struct hvm_ioreq_vcpu *sv, ioreq_t *p) - { -+ unsigned int prev_state = STATE_IOREQ_NONE; -+ - while ( sv->pending ) - { - unsigned int state = p->state; - -- rmb(); -- switch ( state ) -+ smp_rmb(); -+ -+ recheck: -+ if ( unlikely(state == STATE_IOREQ_NONE) ) - { -- case STATE_IOREQ_NONE: - /* - * The only reason we should see this case is when an - * emulator is dying and it races with an I/O being -@@ -102,14 +105,30 @@ static bool hvm_wait_for_io(struct hvm_i - */ - hvm_io_assist(sv, ~0ul); - break; -+ } -+ -+ if ( unlikely(state < prev_state) ) -+ { -+ gdprintk(XENLOG_ERR, "Weird HVM ioreq state transition %u -> %u\n", -+ prev_state, state); -+ sv->pending = false; -+ domain_crash(sv->vcpu->domain); -+ return false; /* bail */ -+ } -+ -+ switch ( prev_state = state ) -+ { - case STATE_IORESP_READY: /* IORESP_READY -> NONE */ - p->state = STATE_IOREQ_NONE; - hvm_io_assist(sv, p->data); - break; - case STATE_IOREQ_READY: /* IOREQ_{READY,INPROCESS} -> IORESP_READY */ - case STATE_IOREQ_INPROCESS: -- wait_on_xen_event_channel(sv->ioreq_evtchn, p->state != state); -- break; -+ wait_on_xen_event_channel(sv->ioreq_evtchn, -+ ({ state = p->state; -+ smp_rmb(); -+ state != prev_state; })); -+ goto recheck; - default: - gdprintk(XENLOG_ERR, "Weird HVM iorequest state %u\n", state); - sv->pending = false; -- cgit v1.2.3