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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,
        Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: [PATCH 4.4 115/162] ACPI: bus: Fix NULL pointer check in acpi_bus_get_private_data()
Date:   Thu, 19 Dec 2019 19:33:43 +0100
Message-Id: <20191219183214.761567085@linuxfoundation.org>
In-Reply-To: <20191219183150.477687052@linuxfoundation.org>
References: <20191219183150.477687052@linuxfoundation.org>
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From: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>

commit 627ead724eff33673597216f5020b72118827de4 upstream.

kmemleak reported backtrace:
    [<bbee0454>] kmem_cache_alloc_trace+0x128/0x260
    [<6677f215>] i2c_acpi_install_space_handler+0x4b/0xe0
    [<1180f4fc>] i2c_register_adapter+0x186/0x400
    [<6083baf7>] i2c_add_adapter+0x4e/0x70
    [<a3ddf966>] intel_gmbus_setup+0x1a2/0x2c0 [i915]
    [<84cb69ae>] i915_driver_probe+0x8d8/0x13a0 [i915]
    [<81911d4b>] i915_pci_probe+0x48/0x160 [i915]
    [<4b159af1>] pci_device_probe+0xdc/0x160
    [<b3c64704>] really_probe+0x1ee/0x450
    [<bc029f5a>] driver_probe_device+0x142/0x1b0
    [<d8829d20>] device_driver_attach+0x49/0x50
    [<de71f045>] __driver_attach+0xc9/0x150
    [<df33ac83>] bus_for_each_dev+0x56/0xa0
    [<80089bba>] driver_attach+0x19/0x20
    [<cc73f583>] bus_add_driver+0x177/0x220
    [<7b29d8c7>] driver_register+0x56/0xf0

In i2c_acpi_remove_space_handler(), a leak occurs whenever the
"data" parameter is initialized to 0 before being passed to
acpi_bus_get_private_data().

This is because the NULL pointer check in acpi_bus_get_private_data()
(condition->if(!*data)) returns EINVAL and, in consequence, memory is
never freed in i2c_acpi_remove_space_handler().

Fix the NULL pointer check in acpi_bus_get_private_data() to follow
the analogous check in acpi_get_data_full().

Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
[ rjw: Subject & changelog ]
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/acpi/bus.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -154,7 +154,7 @@ int acpi_bus_get_private_data(acpi_handl
 {
 	acpi_status status;
 
-	if (!*data)
+	if (!data)
 		return -EINVAL;
 
 	status = acpi_get_data(handle, acpi_bus_private_data_handler, data);