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From: Milan Broz <gmazyland@gmail.com>
To: linux-integrity@vger.kernel.org
Cc: Milan Broz <gmazyland@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] tpm: Fix null pointer dereference on chip register error path
Date: Wed, 12 Jun 2019 10:42:10 +0200	[thread overview]
Message-ID: <20190612084210.13562-1-gmazyland@gmail.com> (raw)

If clk_enable is not defined and chip initialization
is canceled code hits null dereference.

Easily reproducible with vTPM init fail:
  swtpm chardev --tpmstate dir=nonexistent_dir --tpm2 --vtpm-proxy

BUG: kernel NULL pointer dereference, address: 00000000
...
Call Trace:
 tpm_chip_start+0x9d/0xa0 [tpm]
 tpm_chip_register+0x10/0x1a0 [tpm]
 vtpm_proxy_work+0x11/0x30 [tpm_vtpm_proxy]
 process_one_work+0x214/0x5a0
 worker_thread+0x134/0x3e0
 ? process_one_work+0x5a0/0x5a0
 kthread+0xd4/0x100
 ? process_one_work+0x5a0/0x5a0
 ? kthread_park+0x90/0x90
 ret_from_fork+0x19/0x24

Signed-off-by: Milan Broz <gmazyland@gmail.com>
Cc: stable@vger.kernel.org
---
 drivers/char/tpm/tpm-chip.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 90325e1749fb..4c2af643d698 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -95,7 +95,8 @@ int tpm_chip_start(struct tpm_chip *chip)
 	if (chip->locality == -1) {
 		ret = tpm_request_locality(chip);
 		if (ret) {
-			chip->ops->clk_enable(chip, false);
+			if (chip->ops->clk_enable)
+				chip->ops->clk_enable(chip, false);
 			return ret;
 		}
 	}
-- 
2.20.1


             reply	other threads:[~2019-06-12  8:42 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-12  8:42 Milan Broz [this message]
2019-06-12 20:57 ` [PATCH] tpm: Fix null pointer dereference on chip register error path James Morris
2019-06-14 21:56 ` Sasha Levin
2019-06-15  6:28   ` Milan Broz

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