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CVE-2020-36691: netlink: limit recursion depth in policy validation · torvalds/linux@7690aa1
An issue was discovered in the Linux kernel before 5.8. lib/nlattr.c allows attackers to cause a denial of service (unbounded recursion) via a nested Netlink policy with a back reference.
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netlink: limit recursion depth in policy validation
Now that we have nested policies, we can theoretically recurse forever parsing attributes if a (sub-)policy refers back to a higher level one. This is a situation that has happened in nl80211, and we’ve avoided it there by not linking it.
Add some code to netlink parsing to limit recursion depth.
Signed-off-by: Johannes Berg [email protected] Signed-off-by: David S. Miller [email protected]
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