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This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.
Description
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events
After the blamed commit, we started doing this dereference for every
NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER event in the system.
static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
{
struct dsa_user_priv *p = netdev_priv(dev);
return p->dp;
}
Which is obviously bogus, because not all net_devices have a netdev_priv()
of type struct dsa_user_priv. But struct dsa_user_priv is fairly small,
and p->dp means dereferencing 8 bytes starting with offset 16. Most
drivers allocate that much private memory anyway, making our access not
fault, and we discard the bogus data quickly afterwards, so this wasn't
caught.
But the dummy interface is somewhat special in that it calls
alloc_netdev() with a priv size of 0. So every netdev_priv() dereference
is invalid, and we get this when we emit a NETDEV_PRECHANGEUPPER event
with a VLAN as its new upper:
$ ip link add dummy1 type dummy
$ ip link add link dummy1 name dummy1.100 type vlan id 100
[ 43.309174] ==================================================================
[ 43.316456] BUG: KASAN: slab-out-of-bounds in dsa_user_prechangeupper+0x30/0xe8
[ 43.323835] Read of size 8 at addr ffff3f86481d2990 by task ip/374
[ 43.330058]
[ 43.342436] Call trace:
[ 43.366542] dsa_user_prechangeupper+0x30/0xe8
[ 43.371024] dsa_user_netdevice_event+0xb38/0xee8
[ 43.375768] notifier_call_chain+0xa4/0x210
[ 43.379985] raw_notifier_call_chain+0x24/0x38
[ 43.384464] __netdev_upper_dev_link+0x3ec/0x5d8
[ 43.389120] netdev_upper_dev_link+0x70/0xa8
[ 43.393424] register_vlan_dev+0x1bc/0x310
[ 43.397554] vlan_newlink+0x210/0x248
[ 43.401247] rtnl_newlink+0x9fc/0xe30
[ 43.404942] rtnetlink_rcv_msg+0x378/0x580
Avoid the kernel oops by dereferencing after the type check, as customary.
Metrics
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New CVE Received from kernel.org2/23/2024 10:15:09 AM
Action
Type
Old Value
New Value
Added
Description
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events
After the blamed commit, we started doing this dereference for every
NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER event in the system.
static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
{
struct dsa_user_priv *p = netdev_priv(dev);
return p->dp;
}
Which is obviously bogus, because not all net_devices have a netdev_priv()
of type struct dsa_user_priv. But struct dsa_user_priv is fairly small,
and p->dp means dereferencing 8 bytes starting with offset 16. Most
drivers allocate that much private memory anyway, making our access not
fault, and we discard the bogus data quickly afterwards, so this wasn't
caught.
But the dummy interface is somewhat special in that it calls
alloc_netdev() with a priv size of 0. So every netdev_priv() dereference
is invalid, and we get this when we emit a NETDEV_PRECHANGEUPPER event
with a VLAN as its new upper:
$ ip link add dummy1 type dummy
$ ip link add link dummy1 name dummy1.100 type vlan id 100
[ 43.309174] ==================================================================
[ 43.316456] BUG: KASAN: slab-out-of-bounds in dsa_user_prechangeupper+0x30/0xe8
[ 43.323835] Read of size 8 at addr ffff3f86481d2990 by task ip/374
[ 43.330058]
[ 43.342436] Call trace:
[ 43.366542] dsa_user_prechangeupper+0x30/0xe8
[ 43.371024] dsa_user_netdevice_event+0xb38/0xee8
[ 43.375768] notifier_call_chain+0xa4/0x210
[ 43.379985] raw_notifier_call_chain+0x24/0x38
[ 43.384464] __netdev_upper_dev_link+0x3ec/0x5d8
[ 43.389120] netdev_upper_dev_link+0x70/0xa8
[ 43.393424] register_vlan_dev+0x1bc/0x310
[ 43.397554] vlan_newlink+0x210/0x248
[ 43.401247] rtnl_newlink+0x9fc/0xe30
[ 43.404942] rtnetlink_rcv_msg+0x378/0x580
Avoid the kernel oops by dereferencing after the type check, as customary.
Added
Reference
Linux https://git.kernel.org/stable/c/844f104790bd69c2e4dbb9ee3eba46fde1fcea7b [No types assigned]
Added
Reference
Linux https://git.kernel.org/stable/c/dbd909c20c11f0d29c0054d41e0d1f668a60e8c8 [No types assigned]
Quick Info
CVE Dictionary Entry: CVE-2024-26596 NVD
Published Date: 02/23/2024 NVD
Last Modified: 06/17/2026
Source: kernel.org
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