tpm: tpm1_bios_measurements_next should increase position index

stable inclusion
from linux-4.19.116
commit 1da36bedeab0a259d87e782b2adf34c18042a7cd

--------------------------------

commit d7a47b96 upstream.

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

In case of /sys/kernel/security/tpm0/ascii_bios_measurements
and 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: 1f4aace6 ("fs/seq_file.c: simplify seq_file iteration code ...")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283Signed-off-by: NVasily Averin <vvs@virtuozzo.com>
Reviewed-by: NJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: NJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/char/tpm/eventlog/tpm1.c

@@ -129,6 +129,7 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
 	u32 converted_event_size;
 	u32 converted_event_type;
 
+	(*pos)++;
 	converted_event_size = do_endian_conversion(event->event_size);
 
 	v += sizeof(struct tcpa_event) + converted_event_size;
@@ -146,7 +147,6 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
 	    ((v + sizeof(struct tcpa_event) + converted_event_size) >= limit))
 		return NULL;
 
-	(*pos)++;
 	return v;
 }