From: Muhammad Alifa Ramdhan Date: Fri, 3 Apr 2026 01:36:17 +0000 (+0800) Subject: net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9b8b18364fffce4c451e6f6fd218fa4ab646705;p=thirdparty%2Fkernel%2Flinux.git net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption The -EBUSY handling in tls_do_encryption(), introduced by commit 859054147318 ("net: tls: handle backlogging of crypto requests"), has a use-after-free due to double cleanup of encrypt_pending and the scatterlist entry. When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to the cryptd backlog and the async callback tls_encrypt_done() will be invoked upon completion. That callback unconditionally restores the scatterlist entry (sge->offset, sge->length) and decrements ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an error, the synchronous error path in tls_do_encryption() performs the same cleanup again, double-decrementing encrypt_pending and double-restoring the scatterlist. The double-decrement corrupts the encrypt_pending sentinel (initialized to 1), making tls_encrypt_async_wait() permanently skip the wait for pending async callbacks. A subsequent sendmsg can then free the tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still pending, resulting in a use-after-free when the callback fires on the freed record. Fix this by skipping the synchronous cleanup when the -EBUSY async wait returns an error, since the callback has already handled encrypt_pending and sge restoration. Fixes: 859054147318 ("net: tls: handle backlogging of crypto requests") Cc: stable@vger.kernel.org Signed-off-by: Muhammad Alifa Ramdhan Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20260403013617.2838875-1-ramdhan@starlabs.sg Signed-off-by: Paolo Abeni --- diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index dd9dda759bbb..83e78a3d1e65 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -584,6 +584,16 @@ static int tls_do_encryption(struct sock *sk, if (rc == -EBUSY) { rc = tls_encrypt_async_wait(ctx); rc = rc ?: -EINPROGRESS; + /* + * The async callback tls_encrypt_done() has already + * decremented encrypt_pending and restored the sge on + * both success and error. Skip the synchronous cleanup + * below on error, just remove the record and return. + */ + if (rc != -EINPROGRESS) { + list_del(&rec->list); + return rc; + } } if (!rc || rc != -EINPROGRESS) { atomic_dec(&ctx->encrypt_pending);