From: Andrii Nakryiko <andrii@xxxxxxxxxx>
[ Upstream commit 593835377f24ca1bb98008ec1dc3baefe491ad6e ]
add_dst_sec() can invalidate bpf_linker's section index making
dst_symtab pointer pointing into unallocated memory. Reinitialize
dst_symtab pointer on each iteration to make sure it's always valid.
Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs")
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-7-andrii@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/lib/bpf/linker.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 84095a2c2ef2a..6b2f59ddb6918 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -2001,7 +2001,7 @@ add_sym:
static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *obj)
{
struct src_sec *src_symtab = &obj->secs[obj->symtab_sec_idx];
- struct dst_sec *dst_symtab = &linker->secs[linker->symtab_sec_idx];
+ struct dst_sec *dst_symtab;
int i, err;
for (i = 1; i < obj->sec_cnt; i++) {
@@ -2034,6 +2034,9 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
return -1;
}
+ /* add_dst_sec() above could have invalidated linker->secs */
+ dst_symtab = &linker->secs[linker->symtab_sec_idx];
+
/* shdr->sh_link points to SYMTAB */
dst_sec->shdr->sh_link = linker->symtab_sec_idx;
--
2.34.1
