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[PATCH 4.1 43/65] regmap: Fix possible shift overflow in regmap_field_init()

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4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maxime Coquelin <maxime.coquelin@st.com>

commit 921cc29473a0d7c109105c1876ddb432f4a4be7d upstream.

The way the mask is generated in regmap_field_init() is wrong.
Indeed, a field initialized with msb = 31 and lsb = 0 provokes a shift
overflow while calculating the mask field.

On some 32 bits architectures, such as x86, the generated mask is 0,
instead of the expected 0xffffffff.

This patch uses GENMASK() to fix the problem, as this macro is already safe
regarding shift overflow.

Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/base/regmap/regmap.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -945,11 +945,10 @@ EXPORT_SYMBOL_GPL(devm_regmap_init);
 static void regmap_field_init(struct regmap_field *rm_field,
 	struct regmap *regmap, struct reg_field reg_field)
 {
-	int field_bits = reg_field.msb - reg_field.lsb + 1;
 	rm_field->regmap = regmap;
 	rm_field->reg = reg_field.reg;
 	rm_field->shift = reg_field.lsb;
-	rm_field->mask = ((BIT(field_bits) - 1) << reg_field.lsb);
+	rm_field->mask = GENMASK(reg_field.msb, reg_field.lsb);
 	rm_field->id_size = reg_field.id_size;
 	rm_field->id_offset = reg_field.id_offset;
 }


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[PATCH 4.1 00/65] 4.1.3-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:40 +0200
  [PATCH 4.1 43/65] regmap: Fix possible shift overflow in regmap_field_init() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:40 +0200
  [PATCH 4.1 22/65] ALSA: hda - Add a fixup for Dell E7450 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:40 +0200
  [PATCH 4.1 39/65] mm: kmemleak: allow safe memory scanning during kmemleak disabling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:40 +0200
  [PATCH 4.1 04/65] kernfs: Add support for always empty directories. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:40 +0200
  [PATCH 4.1 15/65] ALSA: pcm: Fix pcm_class sysfs output Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 16/65] ALSA: hda - Fix Dock Headphone on Thinkpad X250 seen as a Line Out Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 17/65] ALSA: hda - set proper caps for newer AMD hda audio in KB/KV Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 13/65] ipr: Increase default adapter init stage change timeout Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 11/65] gpio: rcar: Check for irq_set_irq_wake() failures Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 14/65] Disable write buffering on Toshiba ToPIC95 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 12/65] rcu: Correctly handle non-empty Tiny RCU callback list with none ready Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 18/65] ALSA: hda - Disable widget power-save for VIA codecs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  [PATCH 4.1 10/65] gpio: crystalcove: set IRQCHIP_SKIP_SET_WAKE for the irqchip Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-07-19 21:50 +0200
  Re: [PATCH 4.1 00/65] 4.1.3-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2015-07-20 19:20 +0200

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