diff options
| author |   Andrii Nakryiko <andrii@kernel.org> | 2021-11-03 10:32:13 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2021-11-03 13:25:37 -0700 |
| commit | b7332d2820d394dd2ac127df1567b4da597355a1 (patch) | |
| tree | 64263576d847b957e2aecf13e6a9438afa6b852d /tools/lib/bpf/libbpf.c | |
| parent | libbpf: Fix section counting logic (diff) | |
| download | linux-dev-b7332d2820d394dd2ac127df1567b4da597355a1.tar.xz linux-dev-b7332d2820d394dd2ac127df1567b4da597355a1.zip | |
libbpf: Improve ELF relo sanitization
Add few sanity checks for relocations to prevent div-by-zero and
out-of-bounds array accesses in libbpf.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-6-andrii@kernel.org
Diffstat (limited to 'tools/lib/bpf/libbpf.c')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ecfea6c20042..86a44735230e 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3306,6 +3306,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj) } else if (sh->sh_type == SHT_REL) { int targ_sec_idx = sh->sh_info; /* points to other section */ + if (sh->sh_entsize != sizeof(Elf64_Rel) || + targ_sec_idx >= obj->efile.sec_cnt) + return -LIBBPF_ERRNO__FORMAT; + /* Only do relo for section with exec instructions */ if (!section_have_execinstr(obj, targ_sec_idx) && strcmp(name, ".rel" STRUCT_OPS_SEC) && @@ -4025,7 +4029,7 @@ static int bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data) { const char *relo_sec_name, *sec_name; - size_t sec_idx = shdr->sh_info; + size_t sec_idx = shdr->sh_info, sym_idx; struct bpf_program *prog; struct reloc_desc *relos; int err, i, nrels; @@ -4036,6 +4040,9 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Dat Elf64_Sym *sym; Elf64_Rel *rel; + if (sec_idx >= obj->efile.sec_cnt) + return -EINVAL; + scn = elf_sec_by_idx(obj, sec_idx); scn_data = elf_sec_data(obj, scn); @@ -4055,16 +4062,23 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Dat return -LIBBPF_ERRNO__FORMAT; } - sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info)); + sym_idx = ELF64_R_SYM(rel->r_info); + sym = elf_sym_by_idx(obj, sym_idx); if (!sym) { - pr_warn("sec '%s': symbol 0x%zx not found for relo #%d\n", - relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i); + pr_warn("sec '%s': symbol #%zu not found for relo #%d\n", + relo_sec_name, sym_idx, i); + return -LIBBPF_ERRNO__FORMAT; + } + + if (sym->st_shndx >= obj->efile.sec_cnt) { + pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n", + relo_sec_name, sym_idx, (size_t)sym->st_shndx, i); return -LIBBPF_ERRNO__FORMAT; } if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) { pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n", - relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i); + relo_sec_name, (size_t)rel->r_offset, i); return -LIBBPF_ERRNO__FORMAT; } |