Avoid overflow in checking the size of free gaps in vm_map_findspace
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Authored by dougm on Jun 10 2019, 9:53 PM.

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kib
markj
alc

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rS348968: To test to see if a free space is big enough compare the required

Summary

To test to see if a free space is big enough compare the required length to the difference of the two offsets that define the gap, to avoid overflow, rather that adding the length to an offset and comparing that to another offset.

This addresses an overflow issue reported by Peter Holm on i386.

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dougm created this revision.Jun 10 2019, 9:53 PM

Is this a fix for the i386 wrap issue, or just a related change ?

vm_map.c
1802	`(void *)` space before star. Since you are changing format, note that the length is truncated. Perhaps use %ju (I would prefer %jx) and cast to uintmax_t for length.

Change formatting in error log, as suggested.

kib accepted this revision.Jun 11 2019, 2:52 PM

kib added inline comments.

vm_map.c
1801	I suggest %#jx

This revision is now accepted and ready to land.Jun 11 2019, 2:52 PM

I tested this patch on i386 with all of the mmap() tests I have. I also ran the same tests on amd64 plus a buildworld.
I can run a full test if you prefer that.

Closed by commit rS348968: To test to see if a free space is big enough compare the required (authored by dougm). · Explain WhyJun 11 2019, 10:41 PM

This revision was automatically updated to reflect the committed changes.

Herald added a subscriber: imp. · View Herald TranscriptJun 11 2019, 10:41 PM

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vm_map.c

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Avoid overflow in checking the size of free gaps in vm_map_findspaceClosedPublicActions