From: Daniel Borkmann <daniel@iogearbox.net>
Date: Thu, 21 Jan 2016 23:46:28 +0000 (+0100)
Subject: tc, bpf: make sure relo is in relation with map section
X-Git-Tag: v4.5.0~90
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2486337aace9df195eb3d01fb08b665958ce311d;p=thirdparty%2Fiproute2.git

tc, bpf: make sure relo is in relation with map section

Add a test that symbol from relocation entry is actually related
to map section and bail out with an error message if it's not the
case; in relation to [1].

  [1] https://llvm.org/bugs/show_bug.cgi?id=26243

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/tc/tc_bpf.c b/tc/tc_bpf.c
index 42c884186..955bd5fbf 100644
--- a/tc/tc_bpf.c
+++ b/tc/tc_bpf.c
@@ -1328,6 +1328,12 @@ static int bpf_apply_relo_data(struct bpf_elf_ctx *ctx,
 
 		if (gelf_getsym(ctx->sym_tab, GELF_R_SYM(relo.r_info), &sym) != &sym)
 			return -EIO;
+		if (sym.st_shndx != ctx->sec_maps) {
+			fprintf(stderr, "ELF contains non-map related relo data in "
+				"entry %u pointing to section %u! Compiler bug?!\n",
+				relo_ent, sym.st_shndx);
+			return -EIO;
+		}
 
 		rmap = sym.st_value / sizeof(struct bpf_elf_map);
 		if (rmap >= ARRAY_SIZE(ctx->map_fds))