summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJann Horn <jannh@google.com>2023-11-22 22:44:47 +0100
committerJakub Kicinski <kuba@kernel.org>2023-11-23 08:51:45 -0800
commit53f2cb491b500897a619ff6abd72f565933760f0 (patch)
tree29adcd94499633aebf6db4deb2272254aa589eac
parentfd0413bbf8b11f56e8aa842783b0deda0dfe2926 (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>
-rw-r--r--net/tls/tls_sw.c3
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,