129 lines
4.7 KiB
Diff
129 lines
4.7 KiB
Diff
From f0984082067f79b45383fa1eb889c6a901667331 Mon Sep 17 00:00:00 2001
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From: Olivier Fourdan <ofourdan@redhat.com>
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Date: Mon, 20 Jan 2025 17:10:31 +0100
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Subject: [PATCH xserver 4/4] sync: Apply changes last in
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SyncChangeAlarmAttributes()
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SyncChangeAlarmAttributes() would apply the various changes while
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checking for errors.
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If one of the changes triggers an error, the changes for the trigger,
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counter or delta value would remain, possibly leading to inconsistent
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changes.
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Postpone the actual changes until we're sure nothing else can go wrong.
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Related to CVE-2025-26601, ZDI-CAN-25870
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Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
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Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
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---
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Xext/sync.c | 42 +++++++++++++++++++++++++++---------------
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1 file changed, 27 insertions(+), 15 deletions(-)
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diff --git a/Xext/sync.c b/Xext/sync.c
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index c36de1a2e..e282e6657 100644
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--- a/Xext/sync.c
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+++ b/Xext/sync.c
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@@ -800,8 +800,14 @@ SyncChangeAlarmAttributes(ClientPtr client, SyncAlarm * pAlarm, Mask mask,
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int status;
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XSyncCounter counter;
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Mask origmask = mask;
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+ SyncTrigger trigger;
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+ Bool select_events_changed = FALSE;
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+ Bool select_events_value;
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+ int64_t delta;
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- counter = pAlarm->trigger.pSync ? pAlarm->trigger.pSync->id : None;
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+ trigger = pAlarm->trigger;
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+ delta = pAlarm->delta;
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+ counter = trigger.pSync ? trigger.pSync->id : None;
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while (mask) {
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int index2 = lowbit(mask);
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@@ -817,24 +823,24 @@ SyncChangeAlarmAttributes(ClientPtr client, SyncAlarm * pAlarm, Mask mask,
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case XSyncCAValueType:
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mask &= ~XSyncCAValueType;
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/* sanity check in SyncInitTrigger */
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- pAlarm->trigger.value_type = *values++;
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+ trigger.value_type = *values++;
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break;
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case XSyncCAValue:
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mask &= ~XSyncCAValue;
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- pAlarm->trigger.wait_value = ((int64_t)values[0] << 32) | values[1];
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+ trigger.wait_value = ((int64_t)values[0] << 32) | values[1];
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values += 2;
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break;
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case XSyncCATestType:
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mask &= ~XSyncCATestType;
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/* sanity check in SyncInitTrigger */
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- pAlarm->trigger.test_type = *values++;
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+ trigger.test_type = *values++;
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break;
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case XSyncCADelta:
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mask &= ~XSyncCADelta;
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- pAlarm->delta = ((int64_t)values[0] << 32) | values[1];
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+ delta = ((int64_t)values[0] << 32) | values[1];
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values += 2;
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break;
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@@ -844,10 +850,8 @@ SyncChangeAlarmAttributes(ClientPtr client, SyncAlarm * pAlarm, Mask mask,
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client->errorValue = *values;
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return BadValue;
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}
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- status = SyncEventSelectForAlarm(pAlarm, client,
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- (Bool) (*values++));
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- if (status != Success)
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- return status;
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+ select_events_value = (Bool) (*values++);
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+ select_events_changed = TRUE;
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break;
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default:
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@@ -856,25 +860,33 @@ SyncChangeAlarmAttributes(ClientPtr client, SyncAlarm * pAlarm, Mask mask,
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}
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}
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+ if (select_events_changed) {
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+ status = SyncEventSelectForAlarm(pAlarm, client, select_events_value);
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+ if (status != Success)
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+ return status;
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+ }
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+
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/* "If the test-type is PositiveComparison or PositiveTransition
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* and delta is less than zero, or if the test-type is
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* NegativeComparison or NegativeTransition and delta is
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* greater than zero, a Match error is generated."
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*/
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if (origmask & (XSyncCADelta | XSyncCATestType)) {
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- if ((((pAlarm->trigger.test_type == XSyncPositiveComparison) ||
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- (pAlarm->trigger.test_type == XSyncPositiveTransition))
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- && pAlarm->delta < 0)
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+ if ((((trigger.test_type == XSyncPositiveComparison) ||
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+ (trigger.test_type == XSyncPositiveTransition))
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+ && delta < 0)
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||
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- (((pAlarm->trigger.test_type == XSyncNegativeComparison) ||
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- (pAlarm->trigger.test_type == XSyncNegativeTransition))
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- && pAlarm->delta > 0)
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+ (((trigger.test_type == XSyncNegativeComparison) ||
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+ (trigger.test_type == XSyncNegativeTransition))
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+ && delta > 0)
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) {
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return BadMatch;
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}
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}
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/* postpone this until now, when we're sure nothing else can go wrong */
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+ pAlarm->delta = delta;
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+ pAlarm->trigger = trigger;
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if ((status = SyncInitTrigger(client, &pAlarm->trigger, counter, RTCounter,
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origmask & XSyncCAAllTrigger)) != Success)
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return status;
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--
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2.48.1
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