From 07ced7b48219e3bc0c98806f3d7106f86d1b2ca0 Mon Sep 17 00:00:00 2001 From: Peter Hutterer Date: Tue, 17 Jan 2012 21:26:14 +0100 Subject: Force class alignment to a multiple of sizeof(XID). Calculate length field to a multiples of sizeof(XID). XIDs are typedefs to ulong and thus may be 8 bytes on some platforms. This can trigger a SIGBUS if a class ends up not being 8-aligned (e.g. after XAxisInfo). Reported-by: Nicolai Stange Signed-off-by: Peter Hutterer Signed-off-by: Matthieu Herrb --- src/XListDev.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) (limited to 'src') diff --git a/src/XListDev.c b/src/XListDev.c index 6a16da4..6b91238 100644 --- a/src/XListDev.c +++ b/src/XListDev.c @@ -61,6 +61,17 @@ SOFTWARE. #include #include "XIint.h" +/* Calculate length field to a multiples of sizeof(XID). XIDs are typedefs + * to ulong and thus may be 8 bytes on some platforms. This can trigger a + * SIGBUS if a class ends up not being 8-aligned (e.g. after XAxisInfo). + */ +static int pad_to_xid(int base_size) +{ + int padsize = sizeof(XID); + + return ((base_size + padsize - 1)/padsize) * padsize; +} + static int SizeClassInfo(xAnyClassPtr *any, int num_classes) { @@ -69,18 +80,18 @@ SizeClassInfo(xAnyClassPtr *any, int num_classes) for (j = 0; j < num_classes; j++) { switch ((*any)->class) { case KeyClass: - size += sizeof(XKeyInfo); + size += pad_to_xid(sizeof(XKeyInfo)); break; case ButtonClass: - size += sizeof(XButtonInfo); + size += pad_to_xid(sizeof(XButtonInfo)); break; case ValuatorClass: { xValuatorInfoPtr v; v = (xValuatorInfoPtr) *any; - size += sizeof(XValuatorInfo) + - (v->num_axes * sizeof(XAxisInfo)); + size += pad_to_xid(sizeof(XValuatorInfo) + + (v->num_axes * sizeof(XAxisInfo))); break; } default: @@ -105,7 +116,7 @@ ParseClassInfo(xAnyClassPtr *any, XAnyClassPtr *Any, int num_classes) xKeyInfoPtr k = (xKeyInfoPtr) *any; K->class = KeyClass; - K->length = sizeof(XKeyInfo); + K->length = pad_to_xid(sizeof(XKeyInfo)); K->min_keycode = k->min_keycode; K->max_keycode = k->max_keycode; K->num_keys = k->num_keys; @@ -117,7 +128,7 @@ ParseClassInfo(xAnyClassPtr *any, XAnyClassPtr *Any, int num_classes) xButtonInfoPtr b = (xButtonInfoPtr) *any; B->class = ButtonClass; - B->length = sizeof(XButtonInfo); + B->length = pad_to_xid(sizeof(XButtonInfo)); B->num_buttons = b->num_buttons; break; } @@ -129,8 +140,8 @@ ParseClassInfo(xAnyClassPtr *any, XAnyClassPtr *Any, int num_classes) xAxisInfoPtr a; V->class = ValuatorClass; - V->length = sizeof(XValuatorInfo) + - (v->num_axes * sizeof(XAxisInfo)); + V->length = pad_to_xid(sizeof(XValuatorInfo) + + (v->num_axes * sizeof(XAxisInfo))); V->num_axes = v->num_axes; V->motion_buffer = v->motion_buffer_size; V->mode = v->mode; -- cgit v1.2.3