This is a note to let you know that I've just added the patch titled
libbpf: Fix alen calculation in libbpf_nla_dump_errormsg()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
libbpf-fix-alen-calculation-in-libbpf_nla_dump_error.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a1e8b9e7f1e6d21494048dbebd7ac5bb5ce0ff3c
Author: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Date: Fri Feb 10 01:12:01 2023 +0100
libbpf: Fix alen calculation in libbpf_nla_dump_errormsg()
[ 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>
diff --git a/tools/lib/bpf/nlattr.c b/tools/lib/bpf/nlattr.c
index 4719434278b20..ac979b4290559 100644
--- a/tools/lib/bpf/nlattr.c
+++ b/tools/lib/bpf/nlattr.c
@@ -170,7 +170,7 @@ int 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 (nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen, extack_policy) != 0) {
fprintf(stderr,
