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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ahmad Fatoum <a.fatoum@pengutronix.de>,
        =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <mirq-linux@rere.qmqm.pl>,
        Mark Brown <broonie@kernel.org>,
        Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: [PATCH 4.9 39/42] regulator: avoid resolve_supply() infinite recursion
Date:   Tue,  1 Dec 2020 09:53:37 +0100
Message-Id: <20201201084645.740577510@linuxfoundation.org>
In-Reply-To: <20201201084642.194933793@linuxfoundation.org>
References: <20201201084642.194933793@linuxfoundation.org>
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From: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>

commit 4b639e254d3d4f15ee4ff2b890a447204cfbeea9 upstream

When a regulator's name equals its supply's name the
regulator_resolve_supply() recurses indefinitely. Add a check
so that debugging the problem is easier. The "fixed" commit
just exposed the problem.

Fixes: aea6cb99703e ("regulator: resolve supply after creating regulator")
Cc: stable@vger.kernel.org
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # stpmic1
Link: https://lore.kernel.org/r/c6171057cfc0896f950c4d8cb82df0f9f1b89ad9.1605226675.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/regulator/core.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1550,6 +1550,12 @@ static int regulator_resolve_supply(stru
 		}
 	}
 
+	if (r == rdev) {
+		dev_err(dev, "Supply for %s (%s) resolved to itself\n",
+			rdev->desc->name, rdev->supply_name);
+		return -EINVAL;
+	}
+
 	/* Recursively resolve the supply of the supply */
 	ret = regulator_resolve_supply(r);
 	if (ret < 0) {