Re: [PATCH] staging: rts5208: add check on NULL before dereference

[okaya]

On 2018-06-09 12:38, Anton Vasilyev wrote:

If rtsx_probe fails to allocate dev->chip, then NULL pointer
dereference occurs at rtsx_release_resources().

Patch adds checks chip on NULL before its dereference at
rtsx_release_resources and passing with dereference inside
rtsx_release_chip.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev 
---
 drivers/staging/rts5208/rtsx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rts5208/rtsx.c 
b/drivers/staging/rts5208/rtsx.c

index 70e0b8623110..952dd0d580cf 100644
--- a/drivers/staging/rts5208/rtsx.c
+++ b/drivers/staging/rts5208/rtsx.c
@@ -623,12 +623,13 @@ static void rtsx_release_resources(struct 
rtsx_dev *dev)




I think you should bail out if dev->chip is null rather than adding 
conditiinals.




if (dev->irq > 0)
free_irq(dev->irq, (void *)dev);
-   if (dev->chip->msi_en)
+   if (dev->chip && dev->chip->msi_en)
pci_disable_msi(dev->pci);
if (dev->remap_addr)
iounmap(dev->remap_addr);
+   if (dev->chip)
+   rtsx_release_chip(dev->chip);

-   rtsx_release_chip(dev->chip);
kfree(dev->chip);
 }

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Re: [PATCH] staging: rts5208: add check on NULL before dereference

[okaya]

On 2018-06-09 15:34, Andy Shevchenko wrote:

On Sat, Jun 9, 2018 at 7:58 PM,   wrote:

On 2018-06-09 12:38, Anton Vasilyev wrote:


If rtsx_probe fails to allocate dev->chip, then NULL pointer
dereference occurs at rtsx_release_resources().

Patch adds checks chip on NULL before its dereference at
rtsx_release_resources and passing with dereference inside
rtsx_release_chip.

Found by Linux Driver Verification project (linuxtesting.org).



I think you should bail out if dev->chip is null rather than adding
conditiinals.


I'm wondering if it's false positive. At which circumstances that may 
happen?


Only if dev->chip allocation fails. Code tries to cleanup prior 
resources by calling clean_everything() function which ends up in 
rtsx_release_resources()

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