CVE-2022-50301

In the Linux kernel, the following vulnerability has been resolved:

iommu/omap: Fix buffer overflow in debugfs

There are two issues here:

1. The "len" variable needs to be checked before the very first write. Otherwise if omap2_iommu_dump_ctx() with "bytes" less than 32 it is a buffer overflow.
2. The snprintf() function returns the number of bytes that would have been copied if there were enough space. But we want to know the number of bytes which were actually copied so use scnprintf() instead.