WebNov 5, 2024 · Maps. To store and share data between the program and kernel or user spaces, eBPF makes use of maps. As implied by the name, maps are key-value pairs. Supporting a number of different data structures, like hash tables, arrays, and tries, programs are able to send and receive data in maps using helper functions. WebFor example, when a map is created with a key_size of 8 and the eBPF program calls bpf_map_lookup_elem(map_fd, fp - 4) the program will be rejected, since the in-kernel helper function bpf_map_lookup_elem(map_fd, void *key) expects to read 8 bytes from the location pointed to by key, but the fp - 4 (where fp is the top of the stack) starting ...
invalid indirect read from stack off -16+4 size 16 (when …
WebJan 22, 2024 · bpf_check () is a static code analyzer that walks eBPF program instruction by instruction and updates register/stack state. All paths of conditional branches are analyzed until 'bpf_exit' insn. The first pass is depth-first-search to check that the program is a DAG. WebAllow eBPF program to read data from stack only if it wrote into it. BPF_MOV64_REG(BPF_REG_2, BPF_REG_10) ... imm off src dst opcode The invalid opcode is fixed up during programing loading bpf_prog_load(). At this stage the ‘fd’ will be replaced ... libbpf library makes easier to write eBPF programs, red christmas hoodie sprite cranberry
eBPF verifier — The Linux Kernel documentation
WebDiscard is useful for some advanced use-cases, such as ensuring all-or-nothing multi-record submission, or emulating temporary malloc () / free () within single BPF program invocation. Each reserved record is tracked by verifier through existing reference-tracking logic, similar to socket ref-tracking. WebOct 24, 2024 · The verifier complains that, when i=1 (i.e., r1=invP1) and offset=1023 (i.e., R0's umax_value=1023 ), the memory load could read outside of the 1024 bytes of the value. This is easily checked by adding R3's umax_value to R3's off to the access size (1023 + 1 + 1). Root Cause Web0: (7a) * (u64 *) (r10 +8) = 0 invalid stack off=8 size=8 Program that doesn’t initialize stack before passing its address into function: BPF_MOV64_REG (BPF_REG_2, BPF_REG_10), BPF_ALU64_IMM (BPF_ADD, BPF_REG_2, -8), BPF_LD_MAP_FD (BPF_REG_1, 0), BPF_RAW_INSN (BPF_JMP BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), … red christmas headband baby