bspatch: add sanity checks on sizes
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Authored by emaste on Aug 23 2016, 11:26 PM.

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kib
cem
allanjude
delphij
glebius
cperciva

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rS305486: bspatch: add sanity checks on sizes to avoid integer overflow

Summary

Note that on i386 this introduces a new 2GB limit, but this is not a concern in practice. Also avoid allocating an extra byte in the old and new file content buffers.

Based on the "NON-CRYPTANALYTIC ATTACKS AGAINST FREEBSD UPDATE COMPONENTS" gist.

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emaste updated this revision to Diff 19599.Aug 23 2016, 11:26 PM

emaste retitled this revision from to bspatch: add sanity checks on sizes.

emaste updated this object.

emaste edited the test plan for this revision. (Show Details)

emaste added reviewers: allanjude, delphij, glebius.

emaste added a subscriber: cperciva.

delphij added a reviewer: cperciva.Aug 23 2016, 11:29 PM

emaste added inline comments.Aug 23 2016, 11:30 PM

usr.bin/bsdiff/bspatch/bspatch.c
88–90	On i386 ssize_t is 4 bytes, so would truncate from offtin / lseek.
175	`SSIZE_MAX` introduces a 2G limit, but we already had an implicit 2G limit for proper operation based on the previous newsize type.
198–199	Same 2G argument as above.