Attachment 58548 Details for Bug 36108 – Don't copy stale pointers

[patch] Don't copy stale pointers

0001-xf86-modes-Defang-stale-pointers-when-copying-modes.patch (text/plain), 5.17 KB, created by Chris Wilson on 2012-03-16 04:35:36 UTC

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Creator: Chris Wilson

Created: 2012-03-16 04:35:36 UTC

Size: 5.17 KB

patch

obsolete

>From 9f71182e4c5b73a57a25a3f98bce04cdc17fdde3 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Fri, 16 Mar 2012 11:24:12 +0000
>Subject: [PATCH] xf86/modes: Defang stale pointers when copying modes
>
>We stash a copy of the desiredMode on the crtc so that we can restore it
>after a vt switch. This copy is a simple memcpy and so also stashes a
>references to the pointers contained within the desiredMode. Those
>pointers are freed the next time the outputs are probed and mode list
>rebuilt, resulting in us chasing those dangling pointers on the next
>mode switch.
>
>==22787== Invalid read of size 1
>==22787==    at 0x40293C2: __GI_strlen (in
>/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>==22787==    by 0x668F875: strdup (strdup.c:42)
>==22787==    by 0x5DBA00: XNFstrdup (utils.c:1124)
>==22787==    by 0x4D72ED: xf86DuplicateMode (xf86Modes.c:209)
>==22787==    by 0x4CA848: xf86CrtcSetModeTransform (xf86Crtc.c:276)
>==22787==    by 0x4D05B4: xf86SetDesiredModes (xf86Crtc.c:2677)
>==22787==    by 0xA7479D0: sna_create_screen_resources
>(sna_driver.c:220)
>==22787==    by 0x4CB914: xf86CrtcCreateScreenResources (xf86Crtc.c:725)
>==22787==    by 0x425498: main (main.c:216)
>==22787==  Address 0x72c60e0 is 0 bytes inside a block of size 9 free'd
>==22787==    at 0x4027AAE: free (in
>/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>==22787==    by 0x4A547E: xf86DeleteMode (xf86Mode.c:1984)
>==22787==    by 0x4CD84F: xf86ProbeOutputModes (xf86Crtc.c:1578)
>==22787==    by 0x4DC405: xf86RandR12GetInfo12 (xf86RandR12.c:1537)
>==22787==    by 0x518119: RRGetInfo (rrinfo.c:202)
>==22787==    by 0x51D997: rrGetScreenResources (rrscreen.c:335)
>==22787==    by 0x51E0D0: ProcRRGetScreenResources (rrscreen.c:475)
>==22787==    by 0x513852: ProcRRDispatch (randr.c:493)
>==22787==    by 0x4346DB: Dispatch (dispatch.c:439)
>==22787==    by 0x4256E4: main (main.c:287)
>
>Reported-by: Zdenek Kabelac <zdenek.kabelac@gmail.com>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36108
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> hw/xfree86/common/xf86.h       |    1 +
> hw/xfree86/modes/xf86Crtc.c    |    6 +++---
> hw/xfree86/modes/xf86Modes.c   |   11 +++++++++++
> hw/xfree86/modes/xf86RandR12.c |    2 +-
> 4 files changed, 16 insertions(+), 4 deletions(-)
>
>diff --git a/hw/xfree86/common/xf86.h b/hw/xfree86/common/xf86.h
>index b711f05..f83d66f 100644
>--- a/hw/xfree86/common/xf86.h
>+++ b/hw/xfree86/common/xf86.h
>@@ -326,6 +326,7 @@ extern _X_EXPORT double xf86ModeVRefresh(const DisplayModeRec *mode);
> extern _X_EXPORT void xf86SetModeDefaultName(DisplayModePtr mode);
> extern _X_EXPORT void xf86SetModeCrtc(DisplayModePtr p, int adjustFlags);
> extern _X_EXPORT DisplayModePtr xf86DuplicateMode(const DisplayModeRec *pMode);
>+extern _X_EXPORT void xf86InternMode(DisplayModeRec *intern, const DisplayModeRec *mode);
> extern _X_EXPORT DisplayModePtr xf86DuplicateModes(ScrnInfoPtr pScrn, DisplayModePtr modeList);
> extern _X_EXPORT Bool xf86ModesEqual(const DisplayModeRec *pMode1,
> 		    const DisplayModeRec *pMode2);
>diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
>index da9db34..2a94466 100644
>--- a/hw/xfree86/modes/xf86Crtc.c
>+++ b/hw/xfree86/modes/xf86Crtc.c
>@@ -2481,7 +2481,7 @@ xf86InitialConfiguration (ScrnInfoPtr scrn, Bool canGrow)
> 
> 	if (mode && crtc)
> 	{
>-	    crtc->desiredMode = *mode;
>+	    xf86InternMode(&crtc->desiredMode, mode);
> 	    crtc->desiredRotation = output->initial_rotation;
> 	    crtc->desiredX = output->initial_x;
> 	    crtc->desiredY = output->initial_y;
>@@ -2663,7 +2663,7 @@ xf86SetDesiredModes (ScrnInfoPtr scrn)
> 
> 	    if (!mode)
> 		return FALSE;
>-	    crtc->desiredMode = *mode;
>+	    xf86InternMode(&crtc->desiredMode, mode);
> 	    crtc->desiredRotation = RR_Rotate_0;
> 	    crtc->desiredTransformPresent = FALSE;
> 	    crtc->desiredX = 0;
>@@ -2810,7 +2810,7 @@ xf86SetSingleMode (ScrnInfoPtr pScrn, DisplayModePtr desired, Rotation rotation)
> 	    ok = FALSE;
> 	else
> 	{
>-	    crtc->desiredMode = *crtc_mode;
>+	    xf86InternMode(&crtc->desiredMode, crtc_mode);
> 	    crtc->desiredRotation = rotation;
> 	    crtc->desiredTransformPresent = FALSE;
> 	    crtc->desiredX = 0;
>diff --git a/hw/xfree86/modes/xf86Modes.c b/hw/xfree86/modes/xf86Modes.c
>index 49cc149..bc2fdf2 100644
>--- a/hw/xfree86/modes/xf86Modes.c
>+++ b/hw/xfree86/modes/xf86Modes.c
>@@ -212,6 +212,17 @@ xf86DuplicateMode(const DisplayModeRec *pMode)
> }
> 
> /**
>+ * Fills in a copy of mode, removing all stale pointer references.
>+ */
>+void
>+xf86InternMode(DisplayModeRec *intern, const DisplayModeRec *mode)
>+{
>+    *intern = *mode;
>+    intern->prev = intern->next = NULL;
>+    intern->name = NULL;
>+}
>+
>+/**
>  * Duplicates every mode in the given list and returns a pointer to the first
>  * mode.
>  *
>diff --git a/hw/xfree86/modes/xf86RandR12.c b/hw/xfree86/modes/xf86RandR12.c
>index d5031a2..97dc35f 100644
>--- a/hw/xfree86/modes/xf86RandR12.c
>+++ b/hw/xfree86/modes/xf86RandR12.c
>@@ -1236,7 +1236,7 @@ xf86RandR12CrtcSet (ScreenPtr	    pScreen,
> 	    /*
> 	     * Save the last successful setting for EnterVT
> 	     */
>-	    crtc->desiredMode = mode;
>+	    xf86InternMode(&crtc->desiredMode, &mode);
> 	    crtc->desiredRotation = rotation;
> 	    if (transform) {
> 		crtc->desiredTransform = *transform;
>-- 
>1.7.9.1
>

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