FAILED: patch "[PATCH] tpm: fix race condition in tpm_common_write()" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] tpm: fix race condition in tpm_common_write()" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-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>.

thanks,

greg k-h

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

>From 3ab2011ea368ec3433ad49e1b9e1c7b70d2e65df Mon Sep 17 00:00:00 2001
From: Tadeusz Struk <tadeusz.struk@intel.com>
Date: Tue, 22 May 2018 14:37:18 -0700
Subject: [PATCH] tpm: fix race condition in tpm_common_write()

There is a race condition in tpm_common_write function allowing
two threads on the same /dev/tpm<N>, or two different applications
on the same /dev/tpmrm<N> to overwrite each other commands/responses.
Fixed this by taking the priv->buffer_mutex early in the function.

Also converted the priv->data_pending from atomic to a regular size_t
type. There is no need for it to be atomic since it is only touched
under the protection of the priv->buffer_mutex.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index 230b99288024..e4a04b2d3c32 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -37,7 +37,7 @@ static void timeout_work(struct work_struct *work)
 	struct file_priv *priv = container_of(work, struct file_priv, work);
 
 	mutex_lock(&priv->buffer_mutex);
-	atomic_set(&priv->data_pending, 0);
+	priv->data_pending = 0;
 	memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
 	mutex_unlock(&priv->buffer_mutex);
 }
@@ -46,7 +46,6 @@ void tpm_common_open(struct file *file, struct tpm_chip *chip,
 		     struct file_priv *priv)
 {
 	priv->chip = chip;
-	atomic_set(&priv->data_pending, 0);
 	mutex_init(&priv->buffer_mutex);
 	timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
 	INIT_WORK(&priv->work, timeout_work);
@@ -58,29 +57,24 @@ ssize_t tpm_common_read(struct file *file, char __user *buf,
 			size_t size, loff_t *off)
 {
 	struct file_priv *priv = file->private_data;
-	ssize_t ret_size;
-	ssize_t orig_ret_size;
+	ssize_t ret_size = 0;
 	int rc;
 
 	del_singleshot_timer_sync(&priv->user_read_timer);
 	flush_work(&priv->work);
-	ret_size = atomic_read(&priv->data_pending);
-	if (ret_size > 0) {	/* relay data */
-		orig_ret_size = ret_size;
-		if (size < ret_size)
-			ret_size = size;
+	mutex_lock(&priv->buffer_mutex);
 
-		mutex_lock(&priv->buffer_mutex);
+	if (priv->data_pending) {
+		ret_size = min_t(ssize_t, size, priv->data_pending);
 		rc = copy_to_user(buf, priv->data_buffer, ret_size);
-		memset(priv->data_buffer, 0, orig_ret_size);
+		memset(priv->data_buffer, 0, priv->data_pending);
 		if (rc)
 			ret_size = -EFAULT;
 
-		mutex_unlock(&priv->buffer_mutex);
+		priv->data_pending = 0;
 	}
 
-	atomic_set(&priv->data_pending, 0);
-
+	mutex_unlock(&priv->buffer_mutex);
 	return ret_size;
 }
 
@@ -91,17 +85,19 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 	size_t in_size = size;
 	ssize_t out_size;
 
+	if (in_size > TPM_BUFSIZE)
+		return -E2BIG;
+
+	mutex_lock(&priv->buffer_mutex);
+
 	/* Cannot perform a write until the read has cleared either via
 	 * tpm_read or a user_read_timer timeout. This also prevents split
 	 * buffered writes from blocking here.
 	 */
-	if (atomic_read(&priv->data_pending) != 0)
+	if (priv->data_pending != 0) {
+		mutex_unlock(&priv->buffer_mutex);
 		return -EBUSY;
-
-	if (in_size > TPM_BUFSIZE)
-		return -E2BIG;
-
-	mutex_lock(&priv->buffer_mutex);
+	}
 
 	if (copy_from_user
 	    (priv->data_buffer, (void __user *) buf, in_size)) {
@@ -132,7 +128,7 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 		return out_size;
 	}
 
-	atomic_set(&priv->data_pending, out_size);
+	priv->data_pending = out_size;
 	mutex_unlock(&priv->buffer_mutex);
 
 	/* Set a timeout by which the reader must come claim the result */
@@ -149,5 +145,5 @@ void tpm_common_release(struct file *file, struct file_priv *priv)
 	del_singleshot_timer_sync(&priv->user_read_timer);
 	flush_work(&priv->work);
 	file->private_data = NULL;
-	atomic_set(&priv->data_pending, 0);
+	priv->data_pending = 0;
 }
diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h
index ba3b6f9dacf7..b24cfb4d3ee1 100644
--- a/drivers/char/tpm/tpm-dev.h
+++ b/drivers/char/tpm/tpm-dev.h
@@ -8,7 +8,7 @@ struct file_priv {
 	struct tpm_chip *chip;
 
 	/* Data passed to and from the tpm via the read/write calls */
-	atomic_t data_pending;
+	size_t data_pending;
 	struct mutex buffer_mutex;
 
 	struct timer_list user_read_timer;      /* user needs to claim result */

Re: FAILED: patch "[PATCH] tpm: fix race condition in tpm_common_write()" failed to apply to 4.4-stable tree

[Sudip Mukherjee]

[-- Attachment #1: Type: text/plain, Size: 617 bytes --]

Hi Greg,

On Sun, Jul 01, 2018 at 11:34:24AM +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.4-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>.

The attached backported patch should apply to 4.4-stable tree. It will
also apply to 4.9-stable.

It did not apply originally as patch was looking for the splitted files.
The split was done by:
ecb38e2f521b ("tpm: split out tpm-dev.c into tpm-dev.c and tpm-common-dev.c")

--
Regards
Sudip

[-- Attachment #2: 0001-tpm-fix-race-condition-in-tpm_common_write.patch --]
[-- Type: text/x-diff, Size: 4571 bytes --]

>From a8298614c8686b8c9e8706d79a63634cde4684e4 Mon Sep 17 00:00:00 2001
From: Tadeusz Struk <tadeusz.struk@intel.com>
Date: Tue, 22 May 2018 14:37:18 -0700
Subject: [PATCH] tpm: fix race condition in tpm_common_write()

commit 3ab2011ea368ec3433ad49e1b9e1c7b70d2e65df upstream

There is a race condition in tpm_common_write function allowing
two threads on the same /dev/tpm<N>, or two different applications
on the same /dev/tpmrm<N> to overwrite each other commands/responses.
Fixed this by taking the priv->buffer_mutex early in the function.

Also converted the priv->data_pending from atomic to a regular size_t
type. There is no need for it to be atomic since it is only touched
under the protection of the priv->buffer_mutex.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 drivers/char/tpm/tpm-dev.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
index 912ad30be585..98b8a8703a6f 100644
--- a/drivers/char/tpm/tpm-dev.c
+++ b/drivers/char/tpm/tpm-dev.c
@@ -25,7 +25,7 @@ struct file_priv {
 	struct tpm_chip *chip;
 
 	/* Data passed to and from the tpm via the read/write calls */
-	atomic_t data_pending;
+	size_t data_pending;
 	struct mutex buffer_mutex;
 
 	struct timer_list user_read_timer;      /* user needs to claim result */
@@ -46,7 +46,7 @@ static void timeout_work(struct work_struct *work)
 	struct file_priv *priv = container_of(work, struct file_priv, work);
 
 	mutex_lock(&priv->buffer_mutex);
-	atomic_set(&priv->data_pending, 0);
+	priv->data_pending = 0;
 	memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
 	mutex_unlock(&priv->buffer_mutex);
 }
@@ -72,7 +72,6 @@ static int tpm_open(struct inode *inode, struct file *file)
 	}
 
 	priv->chip = chip;
-	atomic_set(&priv->data_pending, 0);
 	mutex_init(&priv->buffer_mutex);
 	setup_timer(&priv->user_read_timer, user_reader_timeout,
 			(unsigned long)priv);
@@ -86,28 +85,24 @@ static ssize_t tpm_read(struct file *file, char __user *buf,
 			size_t size, loff_t *off)
 {
 	struct file_priv *priv = file->private_data;
-	ssize_t ret_size;
+	ssize_t ret_size = 0;
 	int rc;
 
 	del_singleshot_timer_sync(&priv->user_read_timer);
 	flush_work(&priv->work);
-	ret_size = atomic_read(&priv->data_pending);
-	if (ret_size > 0) {	/* relay data */
-		ssize_t orig_ret_size = ret_size;
-		if (size < ret_size)
-			ret_size = size;
+	mutex_lock(&priv->buffer_mutex);
 
-		mutex_lock(&priv->buffer_mutex);
+	if (priv->data_pending) {
+		ret_size = min_t(ssize_t, size, priv->data_pending);
 		rc = copy_to_user(buf, priv->data_buffer, ret_size);
-		memset(priv->data_buffer, 0, orig_ret_size);
+		memset(priv->data_buffer, 0, priv->data_pending);
 		if (rc)
 			ret_size = -EFAULT;
 
-		mutex_unlock(&priv->buffer_mutex);
+		priv->data_pending = 0;
 	}
 
-	atomic_set(&priv->data_pending, 0);
-
+	mutex_unlock(&priv->buffer_mutex);
 	return ret_size;
 }
 
@@ -118,17 +113,19 @@ static ssize_t tpm_write(struct file *file, const char __user *buf,
 	size_t in_size = size;
 	ssize_t out_size;
 
+	if (in_size > TPM_BUFSIZE)
+		return -E2BIG;
+
+	mutex_lock(&priv->buffer_mutex);
+
 	/* cannot perform a write until the read has cleared
 	   either via tpm_read or a user_read_timer timeout.
 	   This also prevents splitted buffered writes from blocking here.
 	*/
-	if (atomic_read(&priv->data_pending) != 0)
+	if (priv->data_pending != 0) {
+		mutex_unlock(&priv->buffer_mutex);
 		return -EBUSY;
-
-	if (in_size > TPM_BUFSIZE)
-		return -E2BIG;
-
-	mutex_lock(&priv->buffer_mutex);
+	}
 
 	if (copy_from_user
 	    (priv->data_buffer, (void __user *) buf, in_size)) {
@@ -153,7 +150,7 @@ static ssize_t tpm_write(struct file *file, const char __user *buf,
 		return out_size;
 	}
 
-	atomic_set(&priv->data_pending, out_size);
+	priv->data_pending = out_size;
 	mutex_unlock(&priv->buffer_mutex);
 
 	/* Set a timeout by which the reader must come claim the result */
@@ -172,7 +169,7 @@ static int tpm_release(struct inode *inode, struct file *file)
 	del_singleshot_timer_sync(&priv->user_read_timer);
 	flush_work(&priv->work);
 	file->private_data = NULL;
-	atomic_set(&priv->data_pending, 0);
+	priv->data_pending = 0;
 	clear_bit(0, &priv->chip->is_open);
 	kfree(priv);
 	return 0;
-- 
2.11.0

Re: FAILED: patch "[PATCH] tpm: fix race condition in tpm_common_write()" failed to apply to 4.4-stable tree

[Greg KH]

On Sun, Aug 12, 2018 at 02:48:34PM +0100, Sudip Mukherjee wrote:
> Hi Greg,
> 
> On Sun, Jul 01, 2018 at 11:34:24AM +0200, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 4.4-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>.
> 
> The attached backported patch should apply to 4.4-stable tree. It will
> also apply to 4.9-stable.
> 
> It did not apply originally as patch was looking for the splitted files.
> The split was done by:
> ecb38e2f521b ("tpm: split out tpm-dev.c into tpm-dev.c and tpm-common-dev.c")
> 
> --
> Regards
> Sudip

> >From a8298614c8686b8c9e8706d79a63634cde4684e4 Mon Sep 17 00:00:00 2001
> From: Tadeusz Struk <tadeusz.struk@intel.com>
> Date: Tue, 22 May 2018 14:37:18 -0700
> Subject: [PATCH] tpm: fix race condition in tpm_common_write()
> 
> commit 3ab2011ea368ec3433ad49e1b9e1c7b70d2e65df upstream
> 
> There is a race condition in tpm_common_write function allowing
> two threads on the same /dev/tpm<N>, or two different applications
> on the same /dev/tpmrm<N> to overwrite each other commands/responses.
> Fixed this by taking the priv->buffer_mutex early in the function.
> 
> Also converted the priv->data_pending from atomic to a regular size_t
> type. There is no need for it to be atomic since it is only touched
> under the protection of the priv->buffer_mutex.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@vger.kernel.org
> Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
> ---
>  drivers/char/tpm/tpm-dev.c | 41 +++++++++++++++++++----------------------
>  1 file changed, 19 insertions(+), 22 deletions(-)

Sorry, but someone already backported this before you did.

thanks,

greg k-h