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From: Cengiz Can <cengiz@kernel.wtf>
To: andy.shevchenko@gmail.com
Cc: cengiz@kernel.wtf, dan.carpenter@oracle.com,
	devel@driverdev.osuosl.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	mchehab@kernel.org, sakari.ailus@linux.intel.com
Subject: [PATCH v6] staging: atomisp: move null check to earlier point
Date: Sun,  2 Aug 2020 01:01:02 +0300
Message-ID: <20200801220101.2783-1-cengiz@kernel.wtf> (raw)
In-Reply-To: <20200731083856.GF3703480@smile.fi.intel.com>

`find_gmin_subdev()` that returns a pointer to `struct
gmin_subdev` can return NULL.

In `gmin_v2p8_ctrl()` there's a call to this function but the
possibility of a NULL was not checked before its being dereferenced,
i.e.:

  /* Acquired here --------v */
  struct gmin_subdev *gs = find_gmin_subdev(subdev);

  /*  v------Dereferenced here */
  if (gs->v2p8_gpio >= 0) {
      ...
  }

With this change we're null checking `find_gmin_subdev()` result
and we return an error if that's the case. We also WARN()
for the sake of debugging.

Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
Reported-by: Coverity Static Analyzer CID 1465536
Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---

 Please do note that this change introduces a new return value to
 `gmin_v2p8_ctrl()`.

 [NEW] - raise a WARN and return -ENODEV if there are no subdevices.
       - return result of `gpio_request` or `gpio_direction_output`.
       - return 0 if GPIO is ON.
       - return results of `regulator_enable` or `regulator_disable`.
       - according to PMIC type, return result of `axp_regulator_set`
         or `gmin_i2c_write`.
       - return -EINVAL if unknown PMIC type.

 Patch Changelog:
   v4: Fix minor typo in commit message
   v5: Remove typo from email subject
   v6: Remove duplicate Signed-off-by tag

 drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
index 0df46a1af5f0..1ad0246764a6 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
+++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
@@ -871,6 +871,9 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int on)
 	int ret;
 	int value;
 
+	if (WARN_ON(!gs))
+		return -ENODEV;
+
 	if (gs->v2p8_gpio >= 0) {
 		pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
 			gs->v2p8_gpio);
@@ -881,7 +884,7 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int on)
 			pr_err("V2P8 GPIO initialization failed\n");
 	}
 
-	if (!gs || gs->v2p8_on == on)
+	if (gs->v2p8_on == on)
 		return 0;
 	gs->v2p8_on = on;
 
-- 
2.27.0


  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-29 13:56 [PATCH] " Cengiz Can
2020-07-29 15:13 ` Andy Shevchenko
2020-07-30  8:45   ` Dan Carpenter
2020-07-30  8:59     ` Cengiz Can
2020-07-30 22:17     ` [PATCH v2] " Cengiz Can
2020-07-31  8:38       ` Andy Shevchenko
2020-08-01 21:51         ` [PATCH v3] " Cengiz Can
2020-08-01 21:55         ` [PATCHi v4] " Cengiz Can
2020-08-01 21:58         ` [PATCH v5] " Cengiz Can
2020-08-01 22:01         ` Cengiz Can [this message]
2020-08-06 18:34           ` [PATCH v6] " Cengiz Can
2020-08-06 18:39             ` Greg KH
2020-08-06 20:38               ` Cengiz Can
2020-08-06 22:15     ` [PATCH] " Bjorn Helgaas
2020-08-07  9:53       ` Dan Carpenter

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