From: Loris Reiff <loris.reiff@liblor.ch>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, kafai@fb.com, songliubraving@fb.com,
yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
sdf@google.com, Loris Reiff <loris.reiff@liblor.ch>
Subject: [PATCH 1/2] bpf: cgroup: Fix optlen WARN_ON_ONCE toctou
Date: Fri, 22 Jan 2021 17:42:31 +0100 [thread overview]
Message-ID: <20210122164232.61770-1-loris.reiff@liblor.ch> (raw)
A toctou issue in `__cgroup_bpf_run_filter_getsockopt` can trigger a
WARN_ON_ONCE in a check of `copy_from_user`.
`*optlen` is checked to be non-negative in the individual getsockopt
functions beforehand. Changing `*optlen` in a race to a negative value
will result in a `copy_from_user(ctx.optval, optval, ctx.optlen)` with
`ctx.optlen` being a negative integer.
Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: Loris Reiff <loris.reiff@liblor.ch>
---
kernel/bpf/cgroup.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 96555a8a2..6ec8f02f4 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1442,6 +1442,11 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
goto out;
}
+ if (ctx.optlen < 0) {
+ ret = -EFAULT;
+ goto out;
+ }
+
if (copy_from_user(ctx.optval, optval,
min(ctx.optlen, max_optlen)) != 0) {
ret = -EFAULT;
--
2.29.2
next reply other threads:[~2021-01-22 17:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 16:42 Loris Reiff [this message]
2021-01-22 16:42 ` [PATCH 2/2] bpf: cgroup: Fix problematic bounds check Loris Reiff
2021-01-22 17:04 ` Stanislav Fomichev
2021-01-22 17:10 ` Loris Reiff
2021-01-22 17:04 ` [PATCH 1/2] bpf: cgroup: Fix optlen WARN_ON_ONCE toctou Stanislav Fomichev
2021-01-22 22:20 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210122164232.61770-1-loris.reiff@liblor.ch \
--to=loris.reiff@liblor.ch \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=john.fastabend@gmail.com \
--cc=kafai@fb.com \
--cc=kpsingh@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=sdf@google.com \
--cc=songliubraving@fb.com \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).