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SubjectRe: [PATCH] hwmon: (w83627ehf): fix broken driver init
On Fri, Nov 04, 2011 at 08:54:10PM -0400, Alexander Beregalov wrote:
> Commit 2265cef2 (hwmon: (w83627ehf) Properly report PECI and AMD-SI
> sensor types) results in kernel panic if data->temp_label was not
> initialized.
> The problem was found with chip W83627DHG-P.
>
> backtrace:
> page_fault()
> w83627ehf_probe() 0x8e2
>
> w83627ehf_init_device:
> 1837: for (i = 0; i < 3; i++) {
> const char *label = data->temp_label[data->temp_src[i]];
>
> /* Digital source overrides analog type */
> if (strncmp(label, "PECI", 4) == 0)
> data->temp_type[i] = 6;
>
> movzbl 128(%r14), %edx # data->temp_src, tmp737
> movq 144(%r13), %rax # data_32->temp_label, data_32->temp_label
> movq $.LC18, %rsi #,
> movl %r14d, %r15d #, i
> subl %r13d, %r15d # D.29277, i
> 0x928 movq (%rax,%rdx,8), %rcx #* data_32->temp_label, label
> movl $4, %edx #,
> movq %rcx, %rdi # label,
> movq %rcx, -96(%rbp) #,
> call strncmp #
>
> page_fault() is called at 0x928 (0x8e2+0x46).
>
Oops ...

> Add check if data->temp->label was set before use.
>
> Cc: Jean Delvare <khali@linux-fr.org>
> Cc: Guenter Roeck <guenter.roeck@ericsson.com>
> Cc: stable@kernel.org
> Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
> ---
> drivers/hwmon/w83627ehf.c | 17 +++++++++--------
> 1 files changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/hwmon/w83627ehf.c b/drivers/hwmon/w83627ehf.c
> index 483cb26..70f1c73 100644
> --- a/drivers/hwmon/w83627ehf.c
> +++ b/drivers/hwmon/w83627ehf.c
> @@ -1835,14 +1835,15 @@ static inline void __devinit w83627ehf_init_device(struct w83627ehf_data *data,
> diode = 0x70;
> }
> for (i = 0; i < 3; i++) {
> - const char *label = data->temp_label[data->temp_src[i]];
> -
> - /* Digital source overrides analog type */
> - if (strncmp(label, "PECI", 4) == 0)
> - data->temp_type[i] = 6;
> - else if (strncmp(label, "AMD", 3) == 0)
> - data->temp_type[i] = 5;
> - else if ((tmp & (0x02 << i)))
> + if (data->temp_label) {
> + const char *label = data->temp_label[data->temp_src[i]];
> +
> + /* Digital source overrides analog type */
> + if (strncmp(label, "PECI", 4) == 0)
> + data->temp_type[i] = 6;
> + else if (strncmp(label, "AMD", 3) == 0)
> + data->temp_type[i] = 5;
> + } else if ((tmp & (0x02 << i)))

This does not completely fix the problem, since there is now an else case which isn't
covered. Specifically, if there is a label, but the source is neither AMD nor PECI,
temp_type won't be set.

Guenter

> data->temp_type[i] = (diode & (0x10 << i)) ? 1 : 3;
> else
> data->temp_type[i] = 4; /* thermistor */
> --
> 1.7.7.2
>


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