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TINSEL: Fix UB for enum TINSEL_EVENT in DW2. PVS-Studio V1016

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In DW2, some large TINSEL_EVENT values are read, and they're bigger than
the last TINSEL_EVENT value, but we cast them to `enum TINSEL_EVENT`
values in tinlib.cpp, which is apparently "unspecified behavior up to
C++17 and undefined behavior starting from C++17".

  tinlib.cpp:1925:39: runtime error: load of value 9041, which is not
     a valid value for type 'Tinsel::TINSEL_EVENT'
  tinlib.cpp:1935:31: runtime error: load of value 77, which is not
     a valid value for type 'Tinsel::TINSEL_EVENT'

Found with UBSan but the really clear help comes from PVS-Studio
documentation.
This commit is contained in:
Donovan Watteau 2022-11-29 00:31:09 +01:00
parent c690a3e985
commit 21cd732b60
1 changed files with 2 additions and 1 deletions
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3
engines/tinsel/events.h
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@ -87,7 +87,8 @@ enum PLR_EVENT {
*
* Note: DW2 renames ENTER & LEAVE to WALKIN & WALKOUT, and has a new LEAVE event
*/
enum TINSEL_EVENT {
// ': int' because out-of-range values happen in DW2 and we do enum casts (PVS-Studio V1016)
enum TINSEL_EVENT : int {
NOEVENT, STARTUP, CLOSEDOWN, POINTED, UNPOINT, WALKIN, WALKOUT,
PICKUP, PUTDOWN, WALKTO, LOOK, ACTION, CONVERSE, SHOWEVENT,
HIDEEVENT, TALKING, ENDTALK, LEAVE_T2, RESTORE, PROV_WALKTO