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[ Upstream commitb9c1e60e7b] None of the JITs is allowed to implement exit paths from the BPF insn mappings other than BPF_JMP | BPF_EXIT. In the BPF core code we have a couple of rewrites in eBPF (e.g. LD_ABS / LD_IND) and in eBPF to cBPF translation to retain old existing behavior where exceptions may occur; they are also tightly controlled by the verifier where it disallows some of the features such as BPF to BPF calls when legacy LD_ABS / LD_IND ops are present in the BPF program. During recent review of all BPF_XADD JIT implementations I noticed that the ppc64 one is buggy in that it contains two jumps to exit paths. This is problematic as this can bypass verifier expectations e.g. pointed out in commitf6b1b3bf0d("bpf: fix subprog verifier bypass by div/mod by 0 exception"). The first exit path is obsoleted by the fix inca36960211("bpf: allow xadd only on aligned memory") anyway, and for the second one we need to do a fetch, add and store loop if the reservation from lwarx/ldarx was lost in the meantime. Fixes:156d0e290e("powerpc/ebpf/jit: Implement JIT compiler for extended BPF") Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Sandipan Das <sandipan@linux.vnet.ibm.com> Tested-by: Sandipan Das <sandipan@linux.vnet.ibm.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>