On 8/3/2010 4:08 PM, Tom Lane wrote:
However, most of the cases that seem of interest so far are in fairly
small, stable functions. Would it be reasonable to attach a "checked
for overflow problems" label to these functions as a whole?
This should work great. I'll get my clang hacker to start
On 8/3/2010 3:43 PM, Tom Lane wrote:
John Regehr writes:
Just to follow up: all the other ones seem to be non-problems.
Would you folks be willing to specify which arithmetic operations are
considered to be safe in the case of overflow? Something simple like an
"INTEGER_OVERFLOW_OK
operation would suffice. This would let me automatically filter out
error messages on these lines of code in the future.
John Regehr
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The following bug has been logged online:
Bug reference: 5592
Logged by: John Regehr
Email address: reg...@cs.utah.edu
PostgreSQL version: head 8/1/10
Operating system: OSX
Description:list of integer undefined behaviors
Details:
Below: a list of integer undefined
Aha-- the -fwrapv flag (which I had though was a nop) screws up our
checks. Another rough edge to fix. Removing this flag caused us to
find a bunch of integer overflows. I'll start reporting them later today.
John
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To make chang
d expect our integer-checked binaries to
be pretty efficient once this is all working.
John
On 8/2/2010 10:16 AM, Tom Lane wrote:
John Regehr writes:
On 08/02/2010 09:06 AM, Tom Lane wrote:
John: how did you detect this?
One of my students has hacked Clang to detect integer undefined
Hrm, I'd have expected you to see a few integer overflows during the
regression tests --- we do test that the overflow checks in places
like int4pl work.
I saw no signed overflows. Our patch still has some rough edges, but
this part is pretty well tested.
Perhaps the int4pl checks fire befor
be able to find more problems if I could get hold of a
good fuzz tester for postgresql, or at least some much larger test
inputs. Are there any of these you folks would suggest that I use?
Thanks,
John
On 08/02/2010 09:06 AM, Tom Lane wrote:
> "John Regehr" writes:
>> Bug
The following bug has been logged online:
Bug reference: 5590
Logged by: John Regehr
Email address: reg...@cs.utah.edu
PostgreSQL version: head 8/2/10
Operating system: OSX
Description:undefined shift behavior
Details:
During a "make check" the left-shif
luence/display/seccode/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
Even if you dislike these, please take a look at the safety checks for
shifts. The current postgresql shift functions need to be strengthened,
and it is easy to do.
John Regehr
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ed behavior for
any argument value. Therefore, any compiler which removes the test is
wrong. Both the GCC and LLVM groups will be happy to fix a bug of that
kind if it exists.
Thanks,
John Regehr
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The following bug has been logged online:
Bug reference: 5416
Logged by: John Regehr
Email address: reg...@cs.utah.edu
PostgreSQL version: git head Apr 12
Operating system: n/a
Description:int4inc() is wrong
Details:
The overflow check in int4inc() from int.c is
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