Bug 98035

Summary: ubsan: misaligned access originating in dbus_message_set_reply_serial()
Product: dbus Reporter: Marc Mutz <marc.mutz>
Component: coreAssignee: D-Bus Maintainers <dbus>
Status: RESOLVED FIXED QA Contact: D-Bus Maintainers <dbus>
Severity: normal    
Priority: medium Keywords: patch
Version: git master   
Hardware: Other   
OS: All   
Whiteboard: review+
i915 platform: i915 features:
Attachments: Git commit fixing the issue.
Revised version

Description Marc Mutz 2016-10-03 21:02:32 UTC 
Created attachment 126981 [details] [review]
Git commit fixing the issue.

UBSan report:

  dbus/dbus/dbus-marshal-basic.c:832:14: runtime error: member access within misaligned address 0x7fdb8dac3a04 for type 'const union DBusBasicValue', which requires 8 byte alignment
  0x7fdb8dac3a04: note: pointer points here
    4a 87 b5 71 01 00 00 00  40 7d 01 00 00 61 00 00  10 3b ac 8d db 7f 00 00  2c 2a 3e 94 db 7f 00 00
                ^
    #0 0x7fdb9444a2c3 in _dbus_marshal_write_basic dbus/dbus/dbus-marshal-basic.c:832
    #1 0x7fdb943d22fb in _dbus_type_writer_write_basic_no_typecode dbus/dbus/dbus-marshal-recursive.c:1605
    #2 0x7fdb943d64e9 in _dbus_type_writer_write_basic dbus/dbus/dbus-marshal-recursive.c:2327
    #3 0x7fdb943c52a6 in write_basic_field dbus/dbus/dbus-marshal-header.c:318
    #4 0x7fdb943c919e in _dbus_header_set_field_basic dbus/dbus/dbus-marshal-header.c:1321
    #5 0x7fdb943e1349 in dbus_message_set_reply_serial dbus/dbus/dbus-message.c:1173

The 'value' parameter to _dbus_header_set_field_basic() is the address of a uint32, which has alignment 4, whereas the union type DBusBasicValue has alignment 8 on 64-bit machines.

Fix attached.
Comment 1 Marc Mutz 2016-10-03 21:05:35 UTC 
Created attachment 126982 [details] [review]
Revised version
Comment 2 Simon McVittie 2016-10-04 10:24:29 UTC 
Looks good, testing now.
Comment 3 Simon McVittie 2016-10-04 19:09:22 UTC 
Fixed in git for 1.10.12 and 1.11.6, thanks!

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