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net: stmmac: ptp: limit n_per_out

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ptp_clock_ops.n_per_out sets the number of PPS outputs, which the PTP
subsystem uses to validate userspace input, such as the index number
used in a PTP_CLK_REQ_PEROUT request.

stmmac_enable() uses this to index the priv->pps array, which is an
array of size STMMAC_PPS_MAX. ptp_clock_ops.n_per_out is initialised
using priv->dma_cap.pps_out_num, which is a three bit field read from
hardware.

Documentation that I've checked suggests that values >= 5 are reserved,
but that doesn't mean such values won't appear, and if they do, we
can overrun the priv->pps array in stmmac_enable().

stmmac_ptp_register() has protection against this in its loop, but it
doesn't act to limit ptp_clock_ops.n_per_out.

Fix this by introducing a local variable, pps_out_num which is limited
to STMMAC_PPS_MAX, and use that when initialising the array and setting
priv->ptp_clock_ops.n_per_out. Print a warning when we limit the number
of outputs.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1vvBhn-0000000ArCg-4C4u@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Russell King (Oracle) 2026-02-25 10:01:19 +00:00 committed by Jakub Kicinski
parent 0314e382cf
commit 5c894879f1
1 changed files with 11 additions and 6 deletions
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17
drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
View File

@ -334,14 +334,19 @@ const struct ptp_clock_info dwmac1000_ptp_clock_ops = {
*/
void stmmac_ptp_register(struct stmmac_priv *priv)
{
unsigned int pps_out_num = priv->dma_cap.pps_out_num;
int i;
for (i = 0; i < priv->dma_cap.pps_out_num; i++) {
if (i >= STMMAC_PPS_MAX)
break;
priv->pps[i].available = true;
if (pps_out_num > STMMAC_PPS_MAX) {
dev_warn(priv->device,
"pps outputs (%u) exceeds driver maximum, limiting to %u\n",
pps_out_num, STMMAC_PPS_MAX);
pps_out_num = STMMAC_PPS_MAX;
}
for (i = 0; i < pps_out_num; i++)
priv->pps[i].available = true;
/* Calculate the clock domain crossing (CDC) error if necessary */
priv->plat->cdc_error_adj = 0;
if (priv->plat->core_type == DWMAC_CORE_GMAC4)
@ -350,8 +355,8 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
/* Update the ptp clock parameters based on feature discovery, when
* available
*/
if (priv->dma_cap.pps_out_num)
priv->ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num;
if (pps_out_num)
priv->ptp_clock_ops.n_per_out = pps_out_num;
if (priv->dma_cap.aux_snapshot_n)
priv->ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n;