diff options
| author | Jann Horn <jannh@google.com> | 2023-11-22 22:44:47 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-11-23 08:51:45 -0800 |
| commit | 53f2cb491b500897a619ff6abd72f565933760f0 (patch) | |
| tree | 29adcd94499633aebf6db4deb2272254aa589eac /net/tls | |
| parent | fd0413bbf8b11f56e8aa842783b0deda0dfe2926 (diff) | |
tls: fix NULL deref on tls_sw_splice_eof() with empty record
syzkaller discovered that if tls_sw_splice_eof() is executed as part of
sendfile() when the plaintext/ciphertext sk_msg are empty, the send path
gets confused because the empty ciphertext buffer does not have enough
space for the encryption overhead. This causes tls_push_record() to go on
the `split = true` path (which is only supposed to be used when interacting
with an attached BPF program), and then get further confused and hit the
tls_merge_open_record() path, which then assumes that there must be at
least one populated buffer element, leading to a NULL deref.
It is possible to have empty plaintext/ciphertext buffers if we previously
bailed from tls_sw_sendmsg_locked() via the tls_trim_both_msgs() path.
tls_sw_push_pending_record() already handles this case correctly; let's do
the same check in tls_sw_splice_eof().
Fixes: df720d288dbb ("tls/sw: Use splice_eof() to flush")
Cc: stable@vger.kernel.org
Reported-by: syzbot+40d43509a099ea756317@syzkaller.appspotmail.com
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20231122214447.675768-1-jannh@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/tls')
| -rw-r--r-- | net/tls/tls_sw.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index a78e8e722409..316f76187962 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1232,11 +1232,14 @@ void tls_sw_splice_eof(struct socket *sock) lock_sock(sk); retry: + /* same checks as in tls_sw_push_pending_record() */ rec = ctx->open_rec; if (!rec) goto unlock; msg_pl = &rec->msg_plaintext; + if (msg_pl->sg.size == 0) + goto unlock; /* Check the BPF advisor and perform transmission. */ ret = bpf_exec_tx_verdict(msg_pl, sk, false, TLS_RECORD_TYPE_DATA, |