crypto: rsa - add a check for allocation failure

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: crypto: rsa - add a check for allocation failure Static checkers insist that the mpi_alloc() allocation can fail so add a check to prevent a NULL dereference. Small allocations like this can't actually fail in current kernels, but adding a check is very simple and makes the static checkers happy.

References

• https://git.kernel.org/stable/c/2831f4d3bfa68e64c5f83e96688be779c87b3511
• https://git.kernel.org/stable/c/95ad8b6879e2e49d02e3bfc0e1fb46421633fe2a
• https://git.kernel.org/stable/c/d872ca165cb67112f2841ef9c37d51ef7e63d1e4