FAILED: patch "[PATCH] tpm: Address !chip->auth in tpm2_*_auth_session()" failed to apply to 6.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.9.y
git checkout FETCH_HEAD
git cherry-pick -x 25ee48a55fd59c72e0bd46dd9160c2d406b5a497
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024070848-graveness-probiotic-9eb0@gregkh' --subject-prefix 'PATCH 6.9.y' HEAD^..

Possible dependencies:

25ee48a55fd5 ("tpm: Address !chip->auth in tpm2_*_auth_session()")
eb24c9788cd9 ("tpm: disable the TPM if NULL name changes")
d0a25bb961e6 ("tpm: Add HMAC session name/handle append")
699e3efd6c64 ("tpm: Add HMAC session start and end functions")
033ee84e5f01 ("tpm: Add TCG mandated Key Derivation Functions (KDFs)")
d2add27cf2b8 ("tpm: Add NULL primary creation")
17d89b2e2f76 ("tpm: Move buffer handling from static inlines to real functions")
cf792e903aff ("tpm: Remove unused tpm_buf_tag()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 25ee48a55fd59c72e0bd46dd9160c2d406b5a497 Mon Sep 17 00:00:00 2001
From: Jarkko Sakkinen <jarkko@kernel.org>
Date: Wed, 3 Jul 2024 19:39:27 +0300
Subject: [PATCH] tpm: Address !chip->auth in tpm2_*_auth_session()

Unless tpm_chip_bootstrap() was called by the driver, !chip->auth can cause
a null derefence in tpm2_*_auth_session(). Thus, address !chip->auth in
tpm2_*_auth_session().

Cc: stable@vger.kernel.org # v6.9+
Reported-by: Stefan Berger <stefanb@linux.ibm.com>
Closes: https://lore.kernel.org/linux-integrity/20240617193408.1234365-1-stefanb@linux.ibm.com/
Fixes: 699e3efd6c64 ("tpm: Add HMAC session start and end functions")
Tested-by: Michael Ellerman <mpe@ellerman.id.au> # ppc
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 907ac9956a78..2f1d96a5a5a7 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -824,8 +824,13 @@ EXPORT_SYMBOL(tpm_buf_check_hmac_response);
  */
 void tpm2_end_auth_session(struct tpm_chip *chip)
 {
-	tpm2_flush_context(chip, chip->auth->handle);
-	memzero_explicit(chip->auth, sizeof(*chip->auth));
+	struct tpm2_auth *auth = chip->auth;
+
+	if (!auth)
+		return;
+
+	tpm2_flush_context(chip, auth->handle);
+	memzero_explicit(auth, sizeof(*auth));
 }
 EXPORT_SYMBOL(tpm2_end_auth_session);
 
@@ -907,6 +912,11 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 	int rc;
 	u32 null_key;
 
+	if (!auth) {
+		dev_warn_once(&chip->dev, "auth session is not active\n");
+		return 0;
+	}
+
 	rc = tpm2_load_null(chip, &null_key);
 	if (rc)
 		goto out;