Affected: Linux

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

arm64: probes: Fix uprobes for big-endian kernels

The arm64 uprobes code is broken for big-endian kernels as it doesn't convert the in-memory instruction encoding (which is always little-endian) into the kernel's native endianness before analyzing and simulating instructions. This may result in a few distinct problems:

* The kernel may may erroneously reject probing an instruction which can safely be probed.

* The kernel may erroneously erroneously permit stepping an instruction out-of-line when that instruction cannot be stepped out-of-line safely.

* The kernel may erroneously simulate instruction incorrectly dur to interpretting the byte-swapped encoding.

The endianness mismatch isn't caught by the compiler or sparse because:

* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so the compiler and sparse have no idea these contain a little-endian 32-bit value. The core uprobes code populates these with a memcpy() which similarly does not handle endianness.

* While the uprobe_opcode_t type is an alias for __le32, both arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[] to the similarly-named probe_opcode_t, which is an alias for u32. Hence there is no endianness conversion warning.

Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and adding the appropriate __le32_to_cpu() conversions prior to consuming the instruction encoding.…