CVE-2024-36971

Description

In the Linux kernel, the following vulnerability has been resolved: net: fix __dst_negative_advice() race __dst_negative_advice() does not enforce proper RCU rules when sk->dst_cache must be cleared, leading to possible UAF. RCU rules are that we must first clear sk->sk_dst_cache, then call dst_release(old_dst). Note that sk_dst_reset(sk) is implementing this protocol correctly, while __dst_negative_advice() uses the wrong order. Given that ip6_negative_advice() has special logic against RTF_CACHE, this means each of the three ->negative_advice() existing methods must perform the sk_dst_reset() themselves. Note the check against NULL dst is centralized in __dst_negative_advice(), there is no need to duplicate it in various callbacks. Many thanks to Clement Lecigne for tracking this issue. This old bug became visible after the blamed commit, using UDP sockets.

Product status

References

https://git.kernel.org/stable/c/051c0bde9f0450a2ec3d62a86d2a0d2fad117f13

https://git.kernel.org/stable/c/db0082825037794c5dba9959c9de13ca34cc5e72

https://git.kernel.org/stable/c/2295a7ef5c8c49241bff769e7826ef2582e532a6

https://git.kernel.org/stable/c/eacb8b195579c174a6d3e12a9690b206eb7f28cf

https://git.kernel.org/stable/c/81dd3c82a456b0015461754be7cb2693991421b4

https://git.kernel.org/stable/c/5af198c387128a9d2ddd620b0f0803564a4d4508

https://git.kernel.org/stable/c/b8af8e6118a6605f0e495a58d591ca94a85a50fc

https://git.kernel.org/stable/c/92f1655aa2b2294d0b49925f3b875a634bd3b59e

cve.org CVE-2024-36971

nvd.nist.gov CVE-2024-36971

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