Fix possible integer overflow #555
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sjaeckel
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Wat? https://github.com/libtom/libtommath/actions/runs/5144260217/jobs/9260336791?pr=555#step:4:333
Do I understand this correctly that |
Yes, it is a good boy^WPRNG. Found it at three places in test.c , so it isn't that bad. |
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I just thought whether it'd be good to add runtime checks&fixups to the |
Changing the output of a PRNG is always *hng* for me but is probably the easiest. How about offering |
absolutely! |
Alhaalta ylös! ;-) Copy&paste a check into every single |
(cherry picked from commit beba892)
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`abs()` can only convert `INT_MIN-1 .. -1` to a positive `int`. Nothing prevents the PRNG to create `INT_MIN` which then leads to a failure of the call to `abs()` as seen in [0]. Instead add an unsigned version of the function reading from the PRNG, so we also don't need to make an absolute value from it. [0] #555 (comment) ``` demo/test.c:1112:13: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself ``` Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>
`abs()` can only convert `INT_MIN-1 .. -1` to a positive `int`. Nothing prevents the PRNG to create `INT_MIN` which then leads to a failure of the call to `abs()` as seen in [0]. Instead add an unsigned version of the function reading from the PRNG, so we also don't need to make an absolute value from it. [0] #555 (comment) ``` demo/test.c:1112:13: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself ``` Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>
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`abs()` can only convert `INT_MIN-1 .. -1` to a positive `int`. Nothing prevents the PRNG to create `INT_MIN` which then leads to a failure of the call to `abs()` as seen in [0]. Instead add an unsigned version of the function reading from the PRNG, so we also don't need to make an absolute value from it. [0] #555 (comment) ``` demo/test.c:1112:13: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself ``` Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>
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In a next step we should follow up on #430 ff. |
This is #546 but on develop.