#5838: integer overflow in rts/RtsUtils:heapOverflow()
-----------------------------------------+----------------------------------
Reporter: hvr | Owner:
Type: bug | Status: new
Priority: normal | Component: Runtime System
Version: 7.2.2 | Keywords:
Os: Unknown/Multiple | Architecture: x86_64 (amd64)
Failure: Incorrect result at runtime | Testcase:
Blockedby: | Blocking:
Related: |
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When failing with a heap exhaustion, the RTS truncates the '''reported'''
''current maximum heap size'' modulo 2^32, e.g.
{{{
$ ghc +RTS -M4G -RTS -e 'sum [1..]'
Heap exhausted;
Current maximum heap size is 0 bytes (0 MB);
use `+RTS -M<size>' to increase it.
}}}
This is most probably due to `OutOfHeapHook()` already being called with
the truncated value from `heapOverflow()`:
{{{
#!c
void
heapOverflow(void)
{
if (!heap_overflow)
{
/* don't fflush(stdout); WORKAROUND bug in Linux glibc */
OutOfHeapHook(0/*unknown request size*/,
RtsFlags.GcFlags.maxHeapSize * BLOCK_SIZE);
heap_overflow = rtsTrue;
}
}
}}}
which multiplies `RtsFlags.GcFlags.maxHeapSize` and `BLOCK_SIZE` whose
type are 32-bit `unsigned int`s, causing the result to be wrapped again
into an `unsigned int`, whereas the result should be upcasted to a `long
unsigned int` (which at least on 64bit archs would be equivalent to a C99
`uint64_t`)
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5838>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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