[PATCH] tpm/eventlog: Use kvmalloc() for event log buffer

[Takashi Iwai <tiwai@suse.de>]

The TPM2 ACPI table may request a large size for the event log, and it
may be over the max size of kmalloc().  When this happens, the driver
spews the kernel WARNING at the probe time, but the error is
eventually ignored in the caller side, and it results in the missing
TPM event log exposure.

This patch replaces the devm_kmalloc() call with kvmalloc() to allow
larger sizes.  Since there is no devm variant for kvmalloc(), now it's
managed manually via devres_alloc() and devres_add().

Reported-and-tested-by: Andy Liang <andy.liang@hpe.com>
Cc: jenifer.golmitz@hpe.com
Link: https://bugzilla.suse.com/show_bug.cgi?id=1232421
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/char/tpm/eventlog/acpi.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
index 69533d0bfb51..56f7d73fa6bf 100644
--- a/drivers/char/tpm/eventlog/acpi.c
+++ b/drivers/char/tpm/eventlog/acpi.c
@@ -63,6 +63,13 @@ static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
 	return n == 0;
 }
 
+static void bios_event_log_release(struct device *dev, void *res)
+{
+	void **logp = res;
+
+	kvfree(*logp);
+}
+
 /* read binary bios log */
 int tpm_read_log_acpi(struct tpm_chip *chip)
 {
@@ -71,6 +78,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	void __iomem *virt;
 	u64 len, start;
 	struct tpm_bios_log *log;
+	void **logp;
 	struct acpi_table_tpm2 *tbl;
 	struct acpi_tpm2_phy *tpm2_phy;
 	int format;
@@ -136,9 +144,16 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	}
 
 	/* malloc EventLog space */
-	log->bios_event_log = devm_kmalloc(&chip->dev, len, GFP_KERNEL);
-	if (!log->bios_event_log)
+	logp = devres_alloc(bios_event_log_release, sizeof(*logp), GFP_KERNEL);
+	if (!logp)
 		return -ENOMEM;
+	devres_add(&chip->dev, logp);
+	log->bios_event_log = kvmalloc(len, GFP_KERNEL);
+	if (!log->bios_event_log) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	*logp = log->bios_event_log;
 
 	log->bios_event_log_end = log->bios_event_log + len;
 
@@ -164,7 +179,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	return format;
 
 err:
-	devm_kfree(&chip->dev, log->bios_event_log);
+	devres_release(&chip->dev, bios_event_log_release, NULL, NULL);
 	log->bios_event_log = NULL;
 	return ret;
 }
-- 
2.43.0