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4708bbda5c
It is not correct to assimilate the elf data of the maps section to an array of map definition. In fact the sizes differ. The offset provided in the symbol section has to be used instead. This patch fixes a bug causing a elf with two maps not to load correctly. Wang Nan added: This patch requires a name for each BPF map, so array of BPF maps is not allowed. This restriction is reasonable, because kernel verifier forbid indexing BPF map from such array unless the index is a fixed value, but if the index is fixed why not merging it into name? For example: Program like this: ... unsigned long cpu = get_smp_processor_id(); int *pval = map_lookup_elem(&map_array[cpu], &key); ... Generates bytecode like this: 0: (b7) r1 = 0 1: (63) *(u32 *)(r10 -4) = r1 2: (b7) r1 = 680997 3: (63) *(u32 *)(r10 -8) = r1 4: (85) call 8 5: (67) r0 <<= 4 6: (18) r1 = 0x112dd000 8: (0f) r0 += r1 9: (bf) r2 = r10 10: (07) r2 += -4 11: (bf) r1 = r0 12: (85) call 1 Where instruction 8 is the computation, 8 and 11 render r1 to an invalid value for function map_lookup_elem, causes verifier report error. Signed-off-by: Eric Leblond <eric@regit.org> Cc: Alexei Starovoitov <ast@fb.com> Cc: He Kuang <hekuang@huawei.com> Cc: Wang Nan <wangnan0@huawei.com> [ Merge bpf_object__init_maps_name into bpf_object__init_maps. Fix segfault for buggy BPF script Validate obj->maps ] Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/20161115040617.69788-5-wangnan0@huawei.com Signed-off-by: Wang Nan <wangnan0@huawei.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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