From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
[ Upstream commit 17bcd27a08a21397698edf143084d7c87ce17946 ]
The code assumes that everything that comes after nlmsgerr are nlattrs.
When calculating their size, it does not account for the initial
nlmsghdr. This may lead to accessing uninitialized memory.
Fixes: bbf48c18ee0c ("libbpf: add error reporting in XDP")
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20230210001210.395194-8-iii@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/lib/bpf/nlattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/lib/bpf/nlattr.c b/tools/lib/bpf/nlattr.c
index b607fa9852b1c..1a04299a2a604 100644
--- a/tools/lib/bpf/nlattr.c
+++ b/tools/lib/bpf/nlattr.c
@@ -178,7 +178,7 @@ int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh)
hlen += nlmsg_len(&err->msg);
attr = (struct nlattr *) ((void *) err + hlen);
- alen = nlh->nlmsg_len - hlen;
+ alen = (void *)nlh + nlh->nlmsg_len - (void *)attr;
if (libbpf_nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen,
extack_policy) != 0) {
--
2.39.2
