nfs4_setup_readdir(): insufficient locking for ->d_parent->d_inode dereferencing

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nfs4_setup_readdir(): insufficient locking for ->d_parent->d_inode dereferencing Theoretically it's an oopsable race, but I don't believe one can manage to hit it on real hardware; might become doable on a KVM, but it still won't be easy to attack. Anyway, it's easy to deal with - since xdr_encode_hyper() is just a call of put_unaligned_be64(), we can put that under ->d_lock and be done with that.

References

• https://git.kernel.org/stable/c/6025f641a0e30afdc5aa62017397b1860ad9f677
• https://git.kernel.org/stable/c/e6cafe71eb3b5579b245ba1bd528a181e77f3df1
• https://git.kernel.org/stable/c/fa4daf7d11e45b72aad5d943a7ab991f869fff79
• https://git.kernel.org/stable/c/504b3fb9948a9e96ebbabdee0d33966a8bab15cb
• https://git.kernel.org/stable/c/eacfd08b26a062f1095b18719715bc82ad35312e
• https://git.kernel.org/stable/c/40be5b9080114f18b0cea386db415b68a7273c1a
• https://git.kernel.org/stable/c/f5e570eaab36a110c6ffda32b87c51170990c2d1
• https://git.kernel.org/stable/c/a890a2e339b929dbd843328f9a92a1625404fe63