From: Alexis Lothoré alexis.lothore@bootlin.com

commit cbefe2ffa7784525ec5d008ba87c7add19ec631a upstream.

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 [ kovalev: bp to fix CVE-2025-38125; replaced netdev_warn with pr_warn due to missing dev pointer ] Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org --- drivers/net/ethernet/stmicro/stmmac/dwmac5.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac5.c b/drivers/net/ethernet/stmicro/stmmac/dwmac5.c index 8fd167501fa0..4df62268f852 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("%s: Invalid PTP rate\n", __func__); + 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);