FAILED: patch "[PATCH] tpm: tpm2_probe: propagate transport errors" failed to apply to 6.1-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.1-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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 7d4f1cbfe063af5581dac66abe9e9c965e1031cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107055340-failed-6.1-7d4f1cbfe063@kernel.org' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Thanks,
Sasha

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

From 7d4f1cbfe063af5581dac66abe9e9c965e1031cc Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Date: Thu, 1 Oct 2026 08:01:11 +0200
Subject: [PATCH] tpm: tpm2_probe: propagate transport errors

tpm2_probe() reads the protocol version from the response tag and is
documented to return -errno on failure, but it always returns 0.  A
transport error (tpm_transmit_cmd() < 0) is thus swallowed together with
the intentionally ignored TPM response code, leaving TPM_CHIP_FLAG_TPM2
unset. A transient bus failure on the first command then misdetects a
TPM 2.0 as a 1.2 and the probe fails on the TPM 1.2 path:

  tpm_tis_i2c 0-002e: 1.2 TPM (device-id 0x1C, rev-id 22)
  tpm tpm0: A TPM error (-62) occurred attempting to determine the timeouts

Return the transport error instead; rc >= 0 still means a valid header was
received and the TPM's own response code is still ignored.

Fixes: 94e266ba1fa3 ("tpm: migrate tpm2_probe() to use struct tpm_buf")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20261001060114.1582092-1-alexander.sverdlin@siemens.com
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm2-cmd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index ae22295df7981..119c73a603e65 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -483,8 +483,9 @@ int tpm2_probe(struct tpm_chip *chip)
 		out = (struct tpm_header *)buf->data;
 		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
 			chip->flags |= TPM_CHIP_FLAG_TPM2;
+		return 0;
 	}
-	return 0;
+	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm2_probe);
 
-- 
2.53.0