select: fix overflow protection #5286

jay · 2020-04-23T19:19:13Z

Follow-up to a96c752 which changed the timeout_ms type from time_t to
timediff_t.

Closes #xxxx

5240 added a change after the review to typecast timeout_ms to time_t but the problem with that is if time_t max is less than timediff_t max then possible signed overflow

Follow-up to a96c752 which changed the timeout_ms type from time_t to timediff_t. Ref: curl#5240 Closes #xxxx

bagder · 2020-04-23T20:12:08Z

lib/select.c

+#if INT_MAX > TIME_T_MAX
+  if(timeout_ms > (int)TIME_T_MAX)
+    timeout_ms = (int)TIME_T_MAX;
+#endif


Can you mention a platform where this change is necessary?

I'm not aware of any platform where INT_MAX > TIME_T_MAX. It's correct to check it though. typecast is because time_t may be unsigned.

While it might be correct to check, curl doesn't build on any platform where int is not 32 bit (and time_t is never smaller than 32 bits either). I'm sure such a theoretical platform would break the curl build in numerous other places. And @mback2k has a larger take on this code in progress anyway. But I won't object if you insist.

Yes I can't think of one. For posterity. #5262 may cover this PR, and if not it can be incorporated. I'll wait to see what happens there.

@jay I would be fine with merging this PR before the release, as my changes will be part of the next feature window.

Ok. I will put this in for now and then you can replace it when you're ready.

Make all functions in select.[ch] take timeout_ms as timediff_t which should always be large enough and signed on all platforms to take all possible timeout values and avoid type conversions. Related to curl#5240 and curl#5286 Replaces curl#5107 and partially curl#5262

Make all functions in select.[ch] take timeout_ms as timediff_t which should always be large enough and signed on all platforms to take all possible timeout values and avoid type conversions. Replaces curl#5107 and partially curl#5262 Related to curl#5240 and curl#5286 Closes curl#5343

Make all functions in select.[ch] take timeout_ms as timediff_t which should always be large enough and signed on all platforms to take all possible timeout values and avoid type conversions. Reviewed-by: Jay Satiro Reviewed-by: Daniel Stenberg Replaces #5107 and partially #5262 Related to #5240 and #5286 Closes #5343

select: fix overflow protection

108fd58

Follow-up to a96c752 which changed the timeout_ms type from time_t to timediff_t. Ref: curl#5240 Closes #xxxx

jay requested a review from bagder April 23, 2020 19:19

bagder reviewed Apr 23, 2020

View reviewed changes

jay closed this in 85eda4e May 2, 2020

jay deleted the fix_select_timeout_overflow branch May 2, 2020 19:10

mback2k mentioned this pull request May 5, 2020

select: use timediff_t instead of time_t and int for timeout_ms #5343

Closed

select: fix overflow protection #5286

select: fix overflow protection #5286

jay commented Apr 23, 2020

bagder Apr 23, 2020

jay Apr 23, 2020 •

edited

bagder Apr 24, 2020 •

edited

jay Apr 24, 2020

mback2k Apr 27, 2020

jay May 2, 2020

select: fix overflow protection #5286

select: fix overflow protection #5286

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jay commented Apr 23, 2020

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jay Apr 23, 2020 •

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