[PATCH v2 0/2] bus: fsl-mc: Fix two double free problems in fsl_mc_device_add()

[PATCH v2 0/2] bus: fsl-mc: Fix two double free problems in fsl_mc_device_add()

[Su Hui]

This patchset fixes two double free problems in fsl_mc_device_add().
One is reported by clang static checker, another is reported by Dan when
reviewing the code.

ps: There is only patch 1 in v1 patch, patch 2 has no v1 version.

v1: https://lore.kernel.org/all/20241114082751.3475110-1-suhui@nfschina.com/

Su Hui (2):
  bus: fsl-mc:  Fix the double free in fsl_mc_device_add()
  bus: fsl-mc: using put_device() when add_device() failed in
    fsl_mc_device_add()

 drivers/bus/fsl-mc/fsl-mc-bus.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

-- 
2.30.2

[PATCH v2 1/2] bus: fsl-mc: Fix the double free in fsl_mc_device_add()

[Su Hui]

Clang static checker(scan-build) warning：
drivers/bus/fsl-mc/fsl-mc-bus.c: line 909, column 2
Attempt to free released memory.

When 'obj_desc->type' == "dprc" and begin to free 'mc_bus' and 'mc_dev',
there is a double free problem because of 'mc_dev = &mc_bus->mc_dev'.
Add a judgment to fix this problem.

Fixes: a042fbed0290 ("staging: fsl-mc: simplify couple of deallocations")
Signed-off-by: Su Hui <suhui@nfschina.com>
---
v2:
 - using is_fsl_mc_bus_dprc().  
 https://lore.kernel.org/all/20241114082751.3475110-1-suhui@nfschina.com/

 drivers/bus/fsl-mc/fsl-mc-bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 930d8a3ba722..319a081a29ef 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -905,8 +905,10 @@ int fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
 
 error_cleanup_dev:
 	kfree(mc_dev->regions);
-	kfree(mc_bus);
-	kfree(mc_dev);
+	if (is_fsl_mc_bus_dprc(mc_dev))
+		kfree(mc_bus);
+	else
+		kfree(mc_dev);
 
 	return error;
 }
-- 
2.30.2

[PATCH v2 2/2] bus: fsl-mc: using put_device() when add_device() failed in fsl_mc_device_add()

[Su Hui]

When device_add(&mc_dev->dev) failed, calling put_device() to let
'mc_dev->dev.release' free the resource rather than goto label
error_cleanup_dev. Otherwise, it can cause double free problem.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/b767348e-d89c-416e-acea-1ebbff3bea20@stanley.mountain/
Fixes: 95b3523b723e ("staging: fsl-mc: add device release callback")
Signed-off-by: Su Hui <suhui@nfschina.com>
---
 drivers/bus/fsl-mc/fsl-mc-bus.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 319a081a29ef..09f8772fed8f 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -895,7 +895,8 @@ int fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
 		dev_err(parent_dev,
 			"device_add() failed for device %s: %d\n",
 			dev_name(&mc_dev->dev), error);
-		goto error_cleanup_dev;
+		put_device(&mc_dev->dev);
+		return error;
 	}
 
 	dev_dbg(parent_dev, "added %s\n", dev_name(&mc_dev->dev));
-- 
2.30.2

Re: [PATCH v2 0/2] bus: fsl-mc: Fix two double free problems in fsl_mc_device_add()

[Dan Carpenter]

On Fri, Nov 15, 2024 at 10:32:05AM +0800, Su Hui wrote:
> This patchset fixes two double free problems in fsl_mc_device_add().
> One is reported by clang static checker, another is reported by Dan when
> reviewing the code.
> 
> ps: There is only patch 1 in v1 patch, patch 2 has no v1 version.
> 
> v1: https://lore.kernel.org/all/20241114082751.3475110-1-suhui@nfschina.com/
> 
> Su Hui (2):
>   bus: fsl-mc:  Fix the double free in fsl_mc_device_add()
>   bus: fsl-mc: using put_device() when add_device() failed in
>     fsl_mc_device_add()

Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>

regards,
dan carpenter