[PATCH 5.10 19/77] net/tls: Fix flipped sign in tls_err_abort() calls

Greg Kroah-Hartman
2021-11-01T09:33:50Z

From: Daniel Jordan <daniel.m.jordan@oracle.com>

commit da353fac65fede6b8b4cfe207f0d9408e3121105 upstream.

sk->sk_err appears to expect a positive value, a convention that ktls
doesn't always follow and that leads to memory corruption in other code.
For instance,

[kworker]
tls_encrypt_done(..., err=<negative error from crypto request>)
tls_err_abort(.., err)
sk->sk_err = err;

[task]
splice_from_pipe_feed
...
tls_sw_do_sendpage
if (sk->sk_err) {
ret = -sk->sk_err; // ret is positive

splice_from_pipe_feed (continued)
ret = actor(...) // ret is still positive and interpreted as bytes
// written, resulting in underflow of buf->len and
// sd->len, leading to huge buf->offset and bogus
// addresses computed in later calls to actor()

Fix all tls_err_abort() callers to pass a negative error code
consistently and centralize the error-prone sign flip there, throwing in
a warning to catch future misuse and uninlining the function so it
really does only warn once.

Cc: stable@vger.kernel.org
Fixes: c46234ebb4d1e ("tls: RX path for ktls")
Reported-by: syzbot+b187b77c8474f9648fae@syzkaller.appspotmail.com
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/tls.h | 9 ++-------
net/tls/tls_sw.c | 17 +++++++++++++----
2 files changed, 15 insertions(+), 11 deletions(-)

--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -359,6 +359,7 @@ int tls_sk_query(struct sock *sk, int op
int __user *optlen);
int tls_sk_attach(struct sock *sk, int optname, char __user *optval,
unsigned int optlen);
+void tls_err_abort(struct sock *sk, int err);

int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx);
void tls_sw_strparser_arm(struct sock *sk, struct tls_context *ctx);
@@ -467,12 +468,6 @@ static inline bool tls_is_sk_tx_device_o
#endif
}

-static inline void tls_err_abort(struct sock *sk, int err)
-{
- sk->sk_err = err;
- sk->sk_error_report(sk);
-}
-
static inline bool tls_bigint_increment(unsigned char *seq, int len)
{
int i;
@@ -513,7 +508,7 @@ static inline void tls_advance_record_sn
struct cipher_context *ctx)
{
if (tls_bigint_increment(ctx->rec_seq, prot->rec_seq_size))
- tls_err_abort(sk, EBADMSG);
+ tls_err_abort(sk, -EBADMSG);

if (prot->version != TLS_1_3_VERSION)
tls_bigint_increment(ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -35,6 +35,7 @@
* SOFTWARE.
*/

+#include <linux/bug.h>
#include <linux/sched/signal.h>
#include <linux/module.h>
#include <linux/splice.h>
@@ -43,6 +44,14 @@
#include <net/strparser.h>
#include <net/tls.h>

+noinline void tls_err_abort(struct sock *sk, int err)
+{
+ WARN_ON_ONCE(err >= 0);
+ /* sk->sk_err should contain a positive error code. */
+ sk->sk_err = -err;
+ sk->sk_error_report(sk);
+}
+
static int __skb_nsg(struct sk_buff *skb, int offset, int len,
unsigned int recursion_level)
{
@@ -419,7 +428,7 @@ int tls_tx_records(struct sock *sk, int

tx_err:
if (rc < 0 && rc != -EAGAIN)
- tls_err_abort(sk, EBADMSG);
+ tls_err_abort(sk, -EBADMSG);

return rc;
}
@@ -764,7 +773,7 @@ static int tls_push_record(struct sock *
msg_pl->sg.size + prot->tail_size, i);
if (rc < 0) {
if (rc != -EINPROGRESS) {
- tls_err_abort(sk, EBADMSG);
+ tls_err_abort(sk, -EBADMSG);
if (split) {
tls_ctx->pending_open_record_frags = true;
tls_merge_open_record(sk, rec, tmp, orig_end);
@@ -1828,7 +1837,7 @@ int tls_sw_recvmsg(struct sock *sk,
err = decrypt_skb_update(sk, skb, &msg->msg_iter,
&chunk, &zc, async_capable);
if (err < 0 && err != -EINPROGRESS) {
- tls_err_abort(sk, EBADMSG);
+ tls_err_abort(sk, -EBADMSG);
goto recv_end;
}

@@ -2008,7 +2017,7 @@ ssize_t tls_sw_splice_read(struct socket
}

if (err < 0) {
- tls_err_abort(sk, EBADMSG);
+ tls_err_abort(sk, -EBADMSG);
goto splice_read_end;
}
ctx->decrypted = 1;