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From: Lee Jones <lee.jones@linaro.org>
To: daniel.thompson@linaro.org, broonie@kernel.org
Cc: baohua@kernel.org, stephan@gerhold.net, arnd@arndb.de,
	linus.walleij@linaro.org, linux-kernel@vger.kernel.org,
	Lee Jones <lee.jones@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 05/10] mfd: mfd-core: Protect against NULL call-back function pointer
Date: Fri,  1 Nov 2019 07:45:13 +0000	[thread overview]
Message-ID: <20191101074518.26228-6-lee.jones@linaro.org> (raw)
In-Reply-To: <20191101074518.26228-1-lee.jones@linaro.org>

If a child device calls mfd_cell_{en,dis}able() without an appropriate
call-back being set, we are likely to encounter a panic.  Avoid this
by adding suitable checking.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
 drivers/mfd/mfd-core.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 23276a80e3b4..96d02b6f06fd 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -28,6 +28,11 @@ int mfd_cell_enable(struct platform_device *pdev)
 	const struct mfd_cell *cell = mfd_get_cell(pdev);
 	int err = 0;
 
+	if (!cell->enable) {
+		dev_dbg(&pdev->dev, "No .enable() call-back registered\n");
+		return 0;
+	}
+
 	/* only call enable hook if the cell wasn't previously enabled */
 	if (atomic_inc_return(cell->usage_count) == 1)
 		err = cell->enable(pdev);
@@ -45,6 +50,11 @@ int mfd_cell_disable(struct platform_device *pdev)
 	const struct mfd_cell *cell = mfd_get_cell(pdev);
 	int err = 0;
 
+	if (!cell->disable) {
+		dev_dbg(&pdev->dev, "No .disable() call-back registered\n");
+		return 0;
+	}
+
 	/* only disable if no other clients are using it */
 	if (atomic_dec_return(cell->usage_count) == 0)
 		err = cell->disable(pdev);
-- 
2.17.1


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  parent reply	other threads:[~2019-11-01  7:46 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01  7:45 [PATCH v4 00/10] Simplify MFD Core Lee Jones
2019-11-01  7:45 ` [PATCH v4 01/10] mfd: cs5535-mfd: Use PLATFORM_DEVID_* defines and tidy error message Lee Jones
2019-11-01  7:45 ` [PATCH v4 02/10] mfd: cs5535-mfd: Remove mfd_cell->id hack Lee Jones
2019-11-01  7:45 ` [PATCH v4 03/10] mfd: cs5535-mfd: Request shared IO regions centrally Lee Jones
2019-11-01  8:01   ` Daniel Thompson
2019-11-01  7:45 ` [PATCH v4 04/10] mfd: cs5535-mfd: Register clients using their own dedicated MFD cell entries Lee Jones
2019-11-01  7:45 ` Lee Jones [this message]
2019-11-01  7:45 ` [PATCH v4 06/10] mfd: mfd-core: Remove mfd_clone_cell() Lee Jones
2019-11-01  7:45 ` [PATCH v4 07/10] x86: olpc-xo1-pm: Remove invocation of MFD's .enable()/.disable() call-backs Lee Jones
2019-11-01  7:45 ` [PATCH v4 08/10] x86: olpc-xo1-sci: " Lee Jones
2019-11-01  7:45 ` [PATCH v4 09/10] mfd: mfd-core: Remove usage counting for .{en, dis}able() call-backs Lee Jones
2019-11-01  7:45 ` [PATCH v4 10/10] mfd: mfd-core: Move pdev->mfd_cell creation back into mfd_add_device() Lee Jones

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