crypto: ccp: Initialize DBC ioctl mutex before registering device

PATCH Superseded Runyu Xiao 4 participants 7 messages Aug 29 – Sep 11

Subsystems (4)

Stable branch Crypto API AMD cryptographic coprocessor (CCP) driver AMD cryptographic coprocessor (CCP) driver - dbc support

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Runyu Xiao

author

2026-08-29 13:34 UTC #0 lore raw

PATCH 1/1 crypto: ccp: Initialize DBC ioctl mutex before registering device

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.

Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.

Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")

Cc [email protected]

Signed-off-by Runyu Xiao <[email protected]>

Assisted-by Codex:GPT-5

---
 drivers/crypto/ccp/dbc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/crypto/ccp/dbc.c +2 -2

index 410084a90..00c864413 100644
@@ -240,12 +240,12 @@ int dbc_dev_init(struct psp_device *psp)
 	dbc_dev->char_dev.name = "dbc";
 	dbc_dev->char_dev.fops = &dbc_fops;
 	dbc_dev->char_dev.mode = 0600;
+	mutex_init(&dbc_dev->ioctl_mutex);
+
 	ret = misc_register(&dbc_dev->char_dev);
 	if (ret)
 		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
 	return 0;
 
 cleanup_mbox:

Tom Lendacky

maintainer

2026-08-29 15:08 UTC #1 lore raw

Quoted 20 lines · Runyu Xiao

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.
Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.
Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")
Cc [email protected]
Signed-off-by Runyu Xiao <[email protected]>
Assisted-by Codex:GPT-5
---
 drivers/crypto/ccp/dbc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/crypto/ccp/dbc.c +0 -0
index 410084a90..00c864413 100644

drivers/crypto/ccp/dbc.c int dbc_dev_init(struct psp_device *psp) · line 243

Quoted 4 lines

drivers/crypto/ccp/dbc.c +1 -0

@@ -240,12 +240,12 @@ int dbc_dev_init(struct psp_device *psp)
 	dbc_dev->char_dev.name = "dbc";
 	dbc_dev->char_dev.fops = &dbc_fops;
 	dbc_dev->char_dev.mode = 0600;
+	mutex_init(&dbc_dev->ioctl_mutex);

This mixes it in with the misc_register() settings and the call, move it to just before all the settings.

Thanks,
Tom

Quoted 10 lines

drivers/crypto/ccp/dbc.c +1 -2

+
 	ret = misc_register(&dbc_dev->char_dev);
 	if (ret)
 		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
 	return 0;
 
 cleanup_mbox:

Runyu Xiao

author

2026-08-30 01:51 UTC #2 lore raw

PATCH v2 1/1 crypto: ccp: Initialize DBC ioctl mutex before registering device

In reply to Runyu Xiao

Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.

Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")

Cc [email protected]

Link https://lore.kernel.org/all/[email protected]/ open here

Signed-off-by Runyu Xiao <[email protected]>

Assisted-by Codex:GPT-5

---
v2:
- Move mutex initialization before setting up the misc device, as suggested by Tom Lendacky.

 drivers/crypto/ccp/dbc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/crypto/ccp/dbc.c +2 -2

index 410084a9039c..4db49a14550c 100644
@@ -235,6 +235,8 @@ int dbc_dev_init(struct psp_device *psp)
 		goto cleanup_mbox;
 	}
 
+	mutex_init(&dbc_dev->ioctl_mutex);
+
 	dbc_dev->char_dev.minor = MISC_DYNAMIC_MINOR;
 	dbc_dev->char_dev.name = "dbc";
 	dbc_dev->char_dev.fops = &dbc_fops;

@@ -243,8 +245,6 @@ int dbc_dev_init(struct psp_device *psp)
 	if (ret)
 		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
 	return 0;
 
 cleanup_mbox:

Tom Lendacky

maintainer Reviewed-by on v2 1/1

2026-08-30 15:19 UTC #3 lore raw

Quoted 4 lines · Runyu Xiao

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.

Quoted 8 lines

Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.
Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")
Cc [email protected]
Link https://lore.kernel.org/all/[email protected]/ open here
Signed-off-by Runyu Xiao <[email protected]>
Assisted-by Codex:GPT-5

Reviewed-by Tom Lendacky <[email protected]>

Quoted 30 lines

---
v2:
- Move mutex initialization before setting up the misc device, as suggested by Tom Lendacky.

 drivers/crypto/ccp/dbc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/crypto/ccp/dbc.c +2 -2

index 410084a9039c..4db49a14550c 100644
@@ -235,6 +235,8 @@ int dbc_dev_init(struct psp_device *psp)
 		goto cleanup_mbox;
 	}
 
+	mutex_init(&dbc_dev->ioctl_mutex);
+
 	dbc_dev->char_dev.minor = MISC_DYNAMIC_MINOR;
 	dbc_dev->char_dev.name = "dbc";
 	dbc_dev->char_dev.fops = &dbc_fops;

@@ -243,8 +245,6 @@ int dbc_dev_init(struct psp_device *psp)
 	if (ret)
 		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
 	return 0;
 
 cleanup_mbox:

Mario Limonciello

Reviewed-by on v2 1/1

2026-08-31 16:08 UTC #4 lore raw

In reply to Runyu Xiao

Quoted 4 lines · Runyu Xiao

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.

Quoted 8 lines

Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.
Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")
Cc [email protected]
Link https://lore.kernel.org/all/[email protected]/ open here
Signed-off-by Runyu Xiao <[email protected]>
Assisted-by Codex:GPT-5

I mean my tag to come here, I didn't realize this was threaded with V1 and V2 together.

Reviewed-by Mario Limonciello (AMD) <[email protected]>> ---

Quoted 29 lines

v2:
- Move mutex initialization before setting up the misc device, as suggested by Tom Lendacky.

  drivers/crypto/ccp/dbc.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

drivers/crypto/ccp/dbc.c +2 -2

index 410084a9039c..4db49a14550c 100644
@@ -235,6 +235,8 @@ int dbc_dev_init(struct psp_device *psp)
  		goto cleanup_mbox;
  	}
 
+	mutex_init(&dbc_dev->ioctl_mutex);
+
  	dbc_dev->char_dev.minor = MISC_DYNAMIC_MINOR;
  	dbc_dev->char_dev.name = "dbc";
  	dbc_dev->char_dev.fops = &dbc_fops;

@@ -243,8 +245,6 @@ int dbc_dev_init(struct psp_device *psp)
  	if (ret)
  		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
  	return 0;
 
  cleanup_mbox:

Herbert Xu

maintainer

2026-09-11 05:32 UTC #5 lore raw

In reply to Runyu Xiao

Quoted 12 lines · Runyu Xiao

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.
Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.
Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")
Cc [email protected]
Link https://lore.kernel.org/all/[email protected]/ open here
Signed-off-by Runyu Xiao <[email protected]>
Assisted-by Codex:GPT-5

Quoted 7 lines

---
v2:
- Move mutex initialization before setting up the misc device, as suggested by Tom Lendacky.
drivers/crypto/ccp/dbc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Patch applied. Thanks.

Signature · 3 lines

Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Mario Limonciello

Reviewed-by on v1 1/1

2026-08-31 16:07 UTC #6 lore raw

In reply to Runyu Xiao

Quoted 11 lines · Runyu Xiao

dbc_dev_init() registers the DBC misc device before initializing ioctl_mutex. Once misc_register() publishes the device, userspace can open it and invoke dbc_ioctl() while the mutex is still uninitialized.
Initialize ioctl_mutex before calling misc_register() so the published ioctl callback always sees an initialized mutex.
Fixes c04cf9e14f10 ("crypto: ccp - Add support for fetching a nonce for dynamic boost control")
Cc [email protected]
Signed-off-by Runyu Xiao <[email protected]>
Assisted-by Codex:GPT-5

Reviewed-by Mario Limonciello (AMD) <[email protected]>> ---

Quoted 22 lines

  drivers/crypto/ccp/dbc.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

drivers/crypto/ccp/dbc.c +2 -2

index 410084a90..00c864413 100644
@@ -240,12 +240,12 @@ int dbc_dev_init(struct psp_device *psp)
  	dbc_dev->char_dev.name = "dbc";
  	dbc_dev->char_dev.fops = &dbc_fops;
  	dbc_dev->char_dev.mode = 0600;
+	mutex_init(&dbc_dev->ioctl_mutex);
+
  	ret = misc_register(&dbc_dev->char_dev);
  	if (ret)
  		goto cleanup_mbox;
 
-	mutex_init(&dbc_dev->ioctl_mutex);
-
  	return 0;
 
  cleanup_mbox: