The memory layout of an XIButtonClassInfo is [struct XIButtonClassInfo][mask][labels]
With the mask being currently 4-byte aligned and labels a list of Atoms. On LP64, Atoms are 8 byte, leading to unaligned access for some mask lengths. Force the alignment to be sizeof(Atom). Reported-by: Christian Weisgerber <na...@mips.inka.de> Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net> --- This should fix the alignment issue but I expect more problems to show up with other calls. XI2 is 4-byte aligned on the wire and that has been taken into the lib. So pretty much anywhere where there's a long or Atom involved, this may cause issues. Some auditing would be good here. Plus, some more generic approach at fixing this than calculating the size by hand everywhere. src/XExtInt.c | 18 ++++++++++++++---- 1 files changed, 14 insertions(+), 4 deletions(-) diff --git a/src/XExtInt.c b/src/XExtInt.c index 5a1bca6..d1451cc 100644 --- a/src/XExtInt.c +++ b/src/XExtInt.c @@ -1028,7 +1028,9 @@ sizeDeviceClassType(int type, int num_elements) case XIButtonClass: l = sizeof(XIButtonClassInfo); l += num_elements * sizeof(Atom); - l += ((((num_elements + 7)/8) + 3)/4) * 4; + /* Force mask alignment with longs to avoid + * unaligned access when accessing the atoms. */ + l += ((((num_elements + 7)/8) + 3)/4) * sizeof(Atom); break; case XIKeyClass: l = sizeof(XIKeyClassInfo); @@ -1121,12 +1123,16 @@ copyDeviceChangedEvent(XGenericEventCookie *in_cookie, { case XIButtonClass: { + int size; XIButtonClassInfo *bin, *bout; bin = (XIButtonClassInfo*)any; bout = next_block(&ptr, sizeof(XIButtonClass)); *bout = *bin; - bout->state.mask = next_block(&ptr, bout->state.mask_len); + /* Force mask alignment with longs to avoid unaligned + * access when accessing the atoms. */ + size = bout->state.mask_len/4 * sizeof(Atom); + bout->state.mask = next_block(&ptr, size); memcpy(bout->state.mask, bin->state.mask, bout->state.mask_len); @@ -1474,14 +1480,18 @@ copy_classes(XIDeviceInfo* to, xXIAnyInfo* from, int nclasses) XIButtonClassInfo *cls_lib; xXIButtonInfo *cls_wire; uint32_t *atoms; + int size; int j; cls_lib = next_block(&ptr_lib, sizeof(XIButtonClassInfo)); cls_wire = (xXIButtonInfo*)any_wire; cls_lib->num_buttons = cls_wire->num_buttons; - cls_lib->state.mask_len = ((((cls_wire->num_buttons + 7)/8) + 3)/4) * 4; - cls_lib->state.mask = next_block(&ptr_lib, cls_lib->state.mask_len); + size = ((((cls_wire->num_buttons + 7)/8) + 3)/4); + cls_lib->state.mask_len = size * 4; + /* Force mask alignment with longs to avoid unaligned + * access when accessing the atoms. */ + cls_lib->state.mask = next_block(&ptr_lib, size * sizeof(Atom)); memcpy(cls_lib->state.mask, &cls_wire[1], cls_lib->state.mask_len); -- 1.7.4 Cheers, Peter _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel