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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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