Re: [PATCH v4] ptp: ocp: Limit signal/freq counts in show/store functions

Sagi Maimon
2025-05-14T06:01:28Z

On Tue, May 13, 2025 at 10:53 PM Vadim Fedorenko
<vadim.fedorenko@linux.dev> wrote:
>
> On 11.05.2025 16:42, Sagi Maimon wrote:
> > The sysfs show/store operations could access uninitialized elements
> > in the freq_in[] and signal_out[] arrays, leading to NULL pointer
> > dereferences. This patch introduces u8 fields (nr_freq_in,
> > nr_signal_out) to track the number of initialized elements, capping
> > the maximum at 4 for each array. The show/store functions are updated
> > to respect these limits, preventing out-of-bounds access and ensuring
> > safe array handling.
> >
> > Signed-off-by: Sagi Maimon <maimon.sagi@gmail.com>
> > ---
> > Addressed comments from Vadim Fedorenko:
> > - https://www.spinics.net/lists/netdev/msg1090730.html
> > Changes since v3:
> > - in signal/freq show routine put constant string "UNSUPPORTED" in
> > output instead of returning error.
> > ---
> > ---
> > drivers/ptp/ptp_ocp.c | 40 +++++++++++++++++++++++++++++++++-------
> > 1 file changed, 33 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
> > index 2ccdca4f6960..14b4b3bebccd 100644
> > --- a/drivers/ptp/ptp_ocp.c
> > +++ b/drivers/ptp/ptp_ocp.c
> > @@ -315,6 +315,8 @@ struct ptp_ocp_serial_port {
> > #define OCP_BOARD_ID_LEN 13
> > #define OCP_SERIAL_LEN 6
> > #define OCP_SMA_NUM 4
> > +#define OCP_SIGNAL_NUM 4
> > +#define OCP_FREQ_NUM 4
> >
> > enum {
> > PORT_GNSS,
> > @@ -342,8 +344,8 @@ struct ptp_ocp {
> > struct dcf_master_reg __iomem *dcf_out;
> > struct dcf_slave_reg __iomem *dcf_in;
> > struct tod_reg __iomem *nmea_out;
> > - struct frequency_reg __iomem *freq_in[4];
> > - struct ptp_ocp_ext_src *signal_out[4];
> > + struct frequency_reg __iomem *freq_in[OCP_FREQ_NUM];
> > + struct ptp_ocp_ext_src *signal_out[OCP_SIGNAL_NUM];
> > struct ptp_ocp_ext_src *pps;
> > struct ptp_ocp_ext_src *ts0;
> > struct ptp_ocp_ext_src *ts1;
> > @@ -378,10 +380,12 @@ struct ptp_ocp {
> > u32 utc_tai_offset;
> > u32 ts_window_adjust;
> > u64 fw_cap;
> > - struct ptp_ocp_signal signal[4];
> > + struct ptp_ocp_signal signal[OCP_SIGNAL_NUM];
> > struct ptp_ocp_sma_connector sma[OCP_SMA_NUM];
> > const struct ocp_sma_op *sma_op;
> > struct dpll_device *dpll;
> > + int signals_nr;
> > + int freq_in_nr;
> > };
> >
> > #define OCP_REQ_TIMESTAMP BIT(0)
> > @@ -2697,6 +2701,8 @@ ptp_ocp_fb_board_init(struct ptp_ocp *bp, struct ocp_resource *r)
> > bp->eeprom_map = fb_eeprom_map;
> > bp->fw_version = ioread32(&bp->image->version);
> > bp->sma_op = &ocp_fb_sma_op;
> > + bp->signals_nr = 4;
> > + bp->freq_in_nr = 4;
> >
> > ptp_ocp_fb_set_version(bp);
> >
> > @@ -2862,6 +2868,8 @@ ptp_ocp_art_board_init(struct ptp_ocp *bp, struct ocp_resource *r)
> > bp->fw_version = ioread32(&bp->reg->version);
> > bp->fw_tag = 2;
> > bp->sma_op = &ocp_art_sma_op;
> > + bp->signals_nr = 4;
> > + bp->freq_in_nr = 4;
> >
> > /* Enable MAC serial port during initialisation */
> > iowrite32(1, &bp->board_config->mro50_serial_activate);
> > @@ -2888,6 +2896,8 @@ ptp_ocp_adva_board_init(struct ptp_ocp *bp, struct ocp_resource *r)
> > bp->flash_start = 0xA00000;
> > bp->eeprom_map = fb_eeprom_map;
> > bp->sma_op = &ocp_adva_sma_op;
> > + bp->signals_nr = 2;
> > + bp->freq_in_nr = 2;
> >
> > version = ioread32(&bp->image->version);
> > /* if lower 16 bits are empty, this is the fw loader. */
> > @@ -3190,6 +3200,9 @@ signal_store(struct device *dev, struct device_attribute *attr,
> > if (!argv)
> > return -ENOMEM;
> >
> > + if (gen >= bp->signals_nr)
> > + return -EINVAL;
> > +
> > err = -EINVAL;
> > s.duty = bp->signal[gen].duty;
> > s.phase = bp->signal[gen].phase;
> > @@ -3247,6 +3260,10 @@ signal_show(struct device *dev, struct device_attribute *attr, char *buf)
> > int i;
> >
> > i = (uintptr_t)ea->var;
> > +
> > + if (i >= bp->signals_nr)
> > + return sysfs_emit(buf, "UNSUPPORTED\n");
> > +
> > signal = &bp->signal[i];
>
> I've checked the code again. Jakub is right, there is no need to modify
> singal/seconds/frequency show/set functions. Now I'm not quite sure how is it
> possible to reach this functions with unsupported input? You export a specific
> set of attributes for your card:
>
> static const struct ocp_attr_group adva_timecard_groups[] = {
> { .cap = OCP_CAP_BASIC, .group = &adva_timecard_group },
> { .cap = OCP_CAP_BASIC, .group = &ptp_ocp_timecard_tty_group },
> { .cap = OCP_CAP_SIGNAL, .group = &fb_timecard_signal0_group },
> { .cap = OCP_CAP_SIGNAL, .group = &fb_timecard_signal1_group },
> { .cap = OCP_CAP_FREQ, .group = &fb_timecard_freq0_group },
> { .cap = OCP_CAP_FREQ, .group = &fb_timecard_freq1_group },
> { },
> };
>
> It has only freq1, freq2, gen1, gen2 attributes exported to sysfs. How can it
> happen that you can change freq3 or gen3?
>
> The only problem I see is in the summary output - that should be addressed with
> this patch (well, you've done it already).
>
you are right the problem can only happen in _signal_summary_show
_frequency_summary_show
> >
> > count = sysfs_emit(buf, "%llu %d %llu %d", signal->period,
> > @@ -3359,6 +3376,9 @@ seconds_store(struct device *dev, struct device_attribute *attr,
> > u32 val;
> > int err;
> >
> > + if (idx >= bp->freq_in_nr)
> > + return -EINVAL;
> > +
> > err = kstrtou32(buf, 0, &val);
> > if (err)
> > return err;
> > @@ -3381,6 +3401,9 @@ seconds_show(struct device *dev, struct device_attribute *attr, char *buf)
> > int idx = (uintptr_t)ea->var;
> > u32 val;
> >
> > + if (idx >= bp->freq_in_nr)
> > + return sysfs_emit(buf, "UNSUPPORTED\n");
> > +
> > val = ioread32(&bp->freq_in[idx]->ctrl);
> > if (val & 1)
> > val = (val >> 8) & 0xff;
> > @@ -3402,6 +3425,9 @@ frequency_show(struct device *dev, struct device_attribute *attr, char *buf)
> > int idx = (uintptr_t)ea->var;
> > u32 val;
> >
> > + if (idx >= bp->freq_in_nr)
> > + return -EINVAL;
> > +
> > val = ioread32(&bp->freq_in[idx]->status);
> > if (val & FREQ_STATUS_ERROR)
> > return sysfs_emit(buf, "error\n");
> > @@ -4008,7 +4034,7 @@ _signal_summary_show(struct seq_file *s, struct ptp_ocp *bp, int nr)
> > {
> > struct signal_reg __iomem *reg = bp->signal_out[nr]->mem;
> > struct ptp_ocp_signal *signal = &bp->signal[nr];
> > - char label[8];
> > + char label[16];
> > bool on;
> > u32 val;
> >
> > @@ -4031,7 +4057,7 @@ static void
> > _frequency_summary_show(struct seq_file *s, int nr,
> > struct frequency_reg __iomem *reg)
> > {
> > - char label[8];
> > + char label[16];
> > bool on;
> > u32 val;
> >
> > @@ -4175,11 +4201,11 @@ ptp_ocp_summary_show(struct seq_file *s, void *data)
> > }
> >
> > if (bp->fw_cap & OCP_CAP_SIGNAL)
> > - for (i = 0; i < 4; i++)
> > + for (i = 0; i < bp->signals_nr; i++)
> > _signal_summary_show(s, bp, i);
> >
> > if (bp->fw_cap & OCP_CAP_FREQ)
> > - for (i = 0; i < 4; i++)
> > + for (i = 0; i < bp->freq_in_nr; i++)
> > _frequency_summary_show(s, i, bp->freq_in[i]);
> >
> > if (bp->irig_out) {
>
> ---
> pw-bot:cr