zebra: Ensure non-equal id's are not same nhg's (backport #16554) #16563
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The function zebra_nhg_hash_equal is only used as a hash function for storage of NHG's and retrieval. If you have say two nhg's: 31 (25/26) 32 (25/26) This function would return them as being equal. Which of course leads to the problem when you attempt to hash_release 32 but release 31 from the hash. Then later when you attempt to do hash comparisons 32 has actually been freed leaving to use after free situations and shit goes down hill fast. This hash is only used as part of the hash comparison function for nexthop group storage. Since this is so let's always return the 31/32 nhg's are not equal at all. We possibly have a different problem where we are creating 31 and 32 ( when 31 should have just been used instead of 32 ) but we need to prevent any type of hash release problem at all. This supercedes any other issue( that should be tracked down on it's own ). Since you can have use after free situation that leads to a crash -vs- some possible nexthop group duplication which is very minor in comparison. Signed-off-by: Donald Sharp <[email protected]> (cherry picked from commit 5a1b61a)
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The function zebra_nhg_hash_equal is only used
as a hash function for storage of NHG's and retrieval. If you have say two nhg's:
31 (25/26)
32 (25/26)
This function would return them as being equal. Which of course leads to the problem when you attempt to hash_release 32 but release 31 from the hash. Then later when you attempt to do hash comparisons 32 has actually been freed leaving to use after free situations and shit goes down hill fast.
This hash is only used as part of the hash comparison function for nexthop group storage. Since this is so let's always return the 31/32 nhg's are not equal at all.
We possibly have a different problem where we are creating 31 and 32 ( when 31 should have just been used instead of 32 ) but we need to prevent any type of hash release problem at all. This supercedes any other issue( that should be tracked down on it's own ). Since you can have use after free situation that leads to a crash -vs- some possible nexthop group duplication which is very minor in comparison.
This is an automatic backport of pull request #16554 done by Mergify.