Patch "regulator: s5m8767: fix get_register() error handling" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

regulator: s5m8767: fix get_register() error handling

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
regulator-s5m8767-fix-get_register-error-handling.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Arnd Bergmann <[email protected]>
Date: Tue, 16 Feb 2016 15:53:11 +0100
Subject: regulator: s5m8767: fix get_register() error handling

From: Arnd Bergmann <[email protected]>

commit e07ff9434167981c993a26d2edbbcb8e13801dbb upstream.

The s5m8767_pmic_probe() function calls s5m8767_get_register() to read data without checking the return code, which produces a compile-time warning when that data is accessed:

drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
drivers/regulator/s5m8767.c:924:7: error: 'enable_reg' may be used uninitialized in this function [-Werror=maybe-uninitialized] drivers/regulator/s5m8767.c:944:30: error: 'enable_val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the s5m8767_get_register() function to return a -EINVAL not just for an invalid register number but also for an invalid regulator number, as both would result in returning uninitialized data. The s5m8767_pmic_probe() function is then changed accordingly to fail on a read error, as all the other callers of s5m8767_get_register() already do.

In practice this probably cannot happen, as we don't call s5m8767_get_register() with invalid arguments, but the gcc warning seems valid in principle, in terms writing safe error checking.

---
 drivers/regulator/s5m8767.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

@@ -202,9 +202,10 @@ static int s5m8767_get_register(struct s
 		}
 	}
 
-	if (i < s5m8767->num_regulators)
-		*enable_ctrl =
-		s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
+	if (i >= s5m8767->num_regulators)
+		return -EINVAL;
+
+	*enable_ctrl = s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
 
 	return 0;
 }

@@ -937,8 +938,12 @@ static int s5m8767_pmic_probe(struct pla
 			else
 				regulators[id].vsel_mask = 0xff;
 
-			s5m8767_get_register(s5m8767, id, &enable_reg,
+			ret = s5m8767_get_register(s5m8767, id, &enable_reg,
 					     &enable_val);
+			if (ret) {
+				dev_err(s5m8767->dev, "error reading registers\n");
+				return ret;
+			}
 			regulators[id].enable_reg = enable_reg;
 			regulators[id].enable_mask = S5M8767_ENCTRL_MASK;
 			regulators[id].enable_val = enable_val;

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/misc-bmp085-enable-building-as-a-module.patch queue-4.5/xen-kconfig-don-t-select-input_xen_kbddev_frontend.patch queue-4.5/regulator-s5m8767-fix-get_register-error-handling.patch queue-4.5/asm-generic-futex-re-enable-preemption-in-futex_atomic_cmpxchg_inatomic.patch queue-4.5/paride-make-verbose-parameter-an-int-again.patch queue-4.5/asoc-s3c24xx-use-const-snd_soc_component_driver-pointer.patch queue-4.5/scsi_dh-force-modular-build-if-scsi-is-a-module.patch