Reject BPF program if uninitialized stack or registers are accessed during interpret path #445
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Reject programs if registers are used before intialized Make undefined behavior check optional Signed-off-by: Alan Jowett <alanjo@microsoft.com>
hawkinsw
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May 21, 2024
Co-authored-by: Will Hawkins <whh8b@obs.cr> Signed-off-by: Alan Jowett <alanjo@microsoft.com>
Signed-off-by: Alan Jowett <alanjo@microsoft.com>
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This pull request includes changes to improve the
ubpflibrary. The most important changes include adding a new libfuzzer based fuzzer, modifying theLLVMFuzzerTestOneInputfunction to compare the results of the interpreter and JIT compiler, adding a bash script to split the fuzzer input into a program and memory, and adding bounds checking for memory accesses.Improvements to fuzzing:
libfuzzer/README.md: Added instructions for building and running a new libfuzzer based fuzzer.libfuzzer/libfuzz_harness.cc: Modified theLLVMFuzzerTestOneInputfunction to compare the results of the interpreter and JIT compiler, and to ensure the program length is a multiple ofsizeof(ebpf_inst). [1] [2]libfuzzer/split.sh: Added a bash script to split the fuzzer input into a program and memory, and to disassemble the program.Improvements to disassembler:
ubpf/disassembler.py: Modified thedisassemble_onefunction to append " local" to the opcode name if the source register is 1. [1] [2]Improvements to JIT compiler:
vm/ubpf_jit_x86_64.c: Added code to truncate the target register to 32 bits for ALU32 instructions.vm/ubpf_jit_x86_64.h: Added theemit_truncate_u32function to emit instructions to truncate a register to 32 bits.Improvements to VM:
vm/ubpf_vm.c: Added bounds checking for memory accesses, and added checks to ensure registers are initialized before they are read. Also fixed a bug in theEBPF_OP_JEQ32_REGinstruction. [1] [2] [3] [4] [5] [6] [7] [8] [9]Resolves: #480