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net: ethtool: fix NULL pointer dereference in phy_reply_size

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In phy_prepare_data(), several strings such as 'name', 'drvname',
'upstream_sfp_name', and 'downstream_sfp_name' are allocated using
kstrdup(). However, these allocations were not checked  for failure.

If kstrdup() fails for 'name', it returns NULL while the function
continues. This leads to a kernel NULL pointer dereference and panic
later in phy_reply_size() when it unconditionally calls strlen() on
the NULL pointer.

While other strings like 'upstream_sfp_name' might be checked before
access in certain code paths, failing to handle these allocations
consistently can lead to incomplete data reporting or hidden bugs.

Fix this by adding proper NULL checks for all kstrdup() calls in
phy_prepare_data() and implement a centralized error handling path
using goto labels to ensure all previously allocated resources are
freed on failure.

Fixes: 9dd2ad5e92 ("net: ethtool: phy: Convert the PHY_GET command to generic phy dump")
Signed-off-by: Quan Sun <2022090917019@std.uestc.edu.cn>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260507131738.1173835-1-2022090917019@std.uestc.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Quan Sun
2026-05-07 21:17:38 +08:00
committed by Jakub Kicinski
parent 0a549298f4
commit 4908f1395f
1 changed files with 30 additions and 2 deletions
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32
net/ethtool/phy.c
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@@ -76,6 +76,7 @@ static int phy_prepare_data(const struct ethnl_req_info *req_info,
struct nlattr **tb = info->attrs;
struct phy_device_node *pdn;
struct phy_device *phydev;
int ret;
/* RTNL is held by the caller */
phydev = ethnl_req_get_phydev(req_info, tb, ETHTOOL_A_PHY_HEADER,
@@ -88,8 +89,17 @@ static int phy_prepare_data(const struct ethnl_req_info *req_info,
return -EOPNOTSUPP;
rep_data->phyindex = phydev->phyindex;
rep_data->name = kstrdup(dev_name(&phydev->mdio.dev), GFP_KERNEL);
if (!rep_data->name)
return -ENOMEM;
rep_data->drvname = kstrdup(phydev->drv->name, GFP_KERNEL);
if (!rep_data->drvname) {
ret = -ENOMEM;
goto err_free_name;
}
rep_data->upstream_type = pdn->upstream_type;
if (pdn->upstream_type == PHY_UPSTREAM_PHY) {
@@ -97,15 +107,33 @@ static int phy_prepare_data(const struct ethnl_req_info *req_info,
rep_data->upstream_index = upstream->phyindex;
}
if (pdn->parent_sfp_bus)
if (pdn->parent_sfp_bus) {
rep_data->upstream_sfp_name = kstrdup(sfp_get_name(pdn->parent_sfp_bus),
GFP_KERNEL);
if (!rep_data->upstream_sfp_name) {
ret = -ENOMEM;
goto err_free_drvname;
}
}
if (phydev->sfp_bus)
if (phydev->sfp_bus) {
rep_data->downstream_sfp_name = kstrdup(sfp_get_name(phydev->sfp_bus),
GFP_KERNEL);
if (!rep_data->downstream_sfp_name) {
ret = -ENOMEM;
goto err_free_upstream_sfp;
}
}
return 0;
err_free_upstream_sfp:
kfree(rep_data->upstream_sfp_name);
err_free_drvname:
kfree(rep_data->drvname);
err_free_name:
kfree(rep_data->name);
return ret;
}
static int phy_fill_reply(struct sk_buff *skb,