[PATCH 6.1 267/280] net: stmmac: make sure that ptp_rate is not 0 before configuring EST

Greg Kroah-Hartman
2026-02-04T15:18:12Z

From: Alexis Lothoré <alexis.lothore@bootlin.com>

[ Upstream commit cbefe2ffa7784525ec5d008ba87c7add19ec631a ]

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@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ The context change is due to the commit c3f3b97238f6
("net: stmmac: Refactor EST implementation")
and the proper adoption is done. ]
Signed-off-by: Rahul Sharma <black.hawk@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/stmicro/stmmac/dwmac5.c | 5 +++++
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c | 5 +++++
2 files changed, 10 insertions(+)

--- 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 *i
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);
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -1497,6 +1497,11 @@ static int dwxgmac3_est_configure(void _
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);