Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
lib/crypto: chacha: Zeroize permuted_state before it leaves scope
Since the ChaCha permutation is invertible, the local variable ‘permuted_state’ is sufficient to compute the original ‘state’, and thus the key, even after the permutation has been done.
While the kernel is quite inconsistent about zeroizing secrets on the stack (and some prominent userspace crypto libraries don’t bother at all since it’s not guaranteed to work anyway), the kernel does try to do it as a best practice, especially in cases involving the RNG.
Thus, explicitly zeroize ‘permuted_state’ before it goes out of scope.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+9 more)
In the Linux kernel, the following vulnerability has been resolved:
lib/crypto: chacha: Zeroize permuted_state before it leaves scope
Since the ChaCha permutation is invertible, the local variable ‘permuted_state’ is sufficient to compute the original ‘state’, and thus the key, even after the permutation has been done.
While the kernel is quite inconsistent about zeroizing secrets on the stack (and some prominent userspace crypto libraries don’t bother at all since it’s not guaranteed to work anyway), the kernel does try to do it as a best practice, especially in cases involving the RNG.
Thus, explicitly zeroize ‘permuted_state’ before it goes out of scope.