From: Alexis Lothoré alexis.lothore@bootlin.com

If the ptp_rate recorded earlier in the driver happens to be 0, this bogus value will propagate up to EST configuration, where it will trigger a division by 0.

Prevent this division by 0 by adding the corresponding check and error code.

Suggested-by: Maxime Chevallier maxime.chevallier@bootlin.com Signed-off-by: Alexis Lothoré alexis.lothore@bootlin.com Fixes: 8572aec3d0dc ("net: stmmac: Add basic EST support for XGMAC") Link: https://patch.msgid.link/20250529-stmmac_tstamp_div-v4-2-d73340a794d5@bootli... Signed-off-by: Jakub Kicinski kuba@kernel.org [ The context change is due to the commit c3f3b97238f6 ("net: stmmac: Refactor EST implementation") which is irrelevant to the logic of this patch. ] Signed-off-by: Rahul Sharma black.hawk@163.com --- drivers/net/ethernet/stmicro/stmmac/dwmac5.c | 5 +++++ drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c | 5 +++++ 2 files changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac5.c b/drivers/net/ethernet/stmicro/stmmac/dwmac5.c index 8fd167501fa0..0afd4644a985 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac5.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac5.c @@ -597,6 +597,11 @@ int dwmac5_est_configure(void __iomem *ioaddr, struct stmmac_est *cfg, int i, ret = 0x0; u32 ctrl;

+ if (!ptp_rate) { + pr_warn("Dwmac5: Invalid PTP rate"); + return -EINVAL; + } + ret |= dwmac5_est_write(ioaddr, BTR_LOW, cfg->btr[0], false); ret |= dwmac5_est_write(ioaddr, BTR_HIGH, cfg->btr[1], false); ret |= dwmac5_est_write(ioaddr, TER, cfg->ter, false); diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c index 0bcb378fa0bc..aab02328a613 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c @@ -1537,6 +1537,11 @@ static int dwxgmac3_est_configure(void __iomem *ioaddr, struct stmmac_est *cfg, int i, ret = 0x0; u32 ctrl;

+ if (!ptp_rate) { + pr_warn("Dwxgmac2: Invalid PTP rate"); + return -EINVAL; + } + ret |= dwxgmac3_est_write(ioaddr, XGMAC_BTR_LOW, cfg->btr[0], false); ret |= dwxgmac3_est_write(ioaddr, XGMAC_BTR_HIGH, cfg->btr[1], false); ret |= dwxgmac3_est_write(ioaddr, XGMAC_TER, cfg->ter, false);