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net: dsa: mxl862xx: fix use-after-free of DSA ports in crc_err_work

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Upon an MDIO CRC error mxl862xx_crc_err_work_fn() walks the DSA ports
and closes the CPU port conduits:

	dsa_switch_for_each_cpu_port(dp, priv->ds)
		dev_close(dp->conduit);

mxl862xx_remove() unregisters the switch before cancelling this work:

	set_bit(MXL862XX_FLAG_WORK_STOPPED, &priv->flags);
	cancel_delayed_work_sync(&priv->stats_work);
	dsa_unregister_switch(ds);
	mxl862xx_host_shutdown(priv);

dsa_unregister_switch() frees the dsa_port objects. If a CRC error
schedules the work during teardown it can run after the ports have been
freed and dereference freed memory.

Guard the port walk with MXL862XX_FLAG_WORK_STOPPED, which is already set
before dsa_unregister_switch(). DSA tears the ports down under
rtnl_lock(), so checking the flag under rtnl_lock() means the work either
runs before teardown and sees valid ports, or runs afterwards, observes
the flag and skips the walk. This mirrors the host_flood_work handler,
which skips torn-down ports under rtnl_lock().

Link: https://sashiko.dev/#/patchset/cover.1780968180.git.daniel%40makrotopia.org?part=2
Fixes: a319d0c8c8 ("net: dsa: mxl862xx: add CRC for MDIO communication")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://patch.msgid.link/5e55169926c02f2b914e5ada529d7453b943cda4.1781702256.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Daniel Golle
2026-06-19 04:40:14 +01:00
committed by Jakub Kicinski
parent 6b3f7af578
commit bcb3b83146
1 changed files with 6 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/net/dsa/mxl862xx/mxl862xx-host.c
View File

@@ -41,12 +41,13 @@ static void mxl862xx_crc_err_work_fn(struct work_struct *work)
crc_err_work);
struct dsa_port *dp;
dev_warn(&priv->mdiodev->dev,
"MDIO CRC error detected, shutting down all ports\n");
rtnl_lock();
dsa_switch_for_each_cpu_port(dp, priv->ds)
dev_close(dp->conduit);
if (!test_bit(MXL862XX_FLAG_WORK_STOPPED, &priv->flags)) {
dev_warn(&priv->mdiodev->dev,
"MDIO CRC error detected, shutting down all ports\n");
dsa_switch_for_each_cpu_port(dp, priv->ds)
dev_close(dp->conduit);
}
rtnl_unlock();
clear_bit(MXL862XX_FLAG_CRC_ERR, &priv->flags);