From f9bf8adb55cd5a357b247a16aafddf8c97b276e0 Mon Sep 17 00:00:00 2001
From: Vasily Averin <vvs@virtuozzo.com>
Date: Tue, 25 Feb 2020 09:26:22 +0300
Subject: [PATCH] tpm: tpm2_bios_measurements_next should increase position index
Git-commit: f9bf8adb55cd5a357b247a16aafddf8c97b276e0
Patch-mainline: v5.7-rc1
References: git-fixes

If .next function does not change position index,
following .show function will repeat output related
to current position index.

For /sys/kernel/security/tpm0/binary_bios_measurements:
1) read after lseek beyound end of file generates whole last line.
2) read after lseek to middle of last line generates
expected end of last line and unexpected whole last line once again.

Cc: stable@vger.kernel.org # 4.19.x
Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code ...")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/char/tpm/eventlog/tpm2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/tpm/eventlog/tpm2.c b/drivers/char/tpm/eventlog/tpm2.c
index b9aeda1cbcd7..e741b1157525 100644
--- a/drivers/char/tpm/eventlog/tpm2.c
+++ b/drivers/char/tpm/eventlog/tpm2.c
@@ -94,6 +94,7 @@ static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
 	size_t event_size;
 	void *marker;
 
+	(*pos)++;
 	event_header = log->bios_event_log;
 
 	if (v == SEQ_START_TOKEN) {
@@ -118,7 +119,6 @@ static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
 	if (((v + event_size) >= limit) || (event_size == 0))
 		return NULL;
 
-	(*pos)++;
 	return v;
 }
 
-- 
2.16.4