Bug 2424967 (CVE-2023-53995)

Summary: CVE-2023-53995 kernel: Linux kernel: Denial of Service due to memory leak in IP address deletion
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel. An incorrect handling of the 'last_prim' value within the __inet_del_ifa() function during IP address deletion can be triggered by a local user. This memory leak leads to resource exhaustion, potentially causing a Denial of Service (DoS) on the system.
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Description OSIDB Bzimport 2025-12-24 12:04:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: ipv4: fix one memleak in __inet_del_ifa()

I got the below warning when do fuzzing test:
unregister_netdevice: waiting for bond0 to become free. Usage count = 2

It can be repoduced via:

ip link add bond0 type bond
sysctl -w net.ipv4.conf.bond0.promote_secondaries=1
ip addr add 4.117.174.103/0 scope 0x40 dev bond0
ip addr add 192.168.100.111/255.255.255.254 scope 0 dev bond0
ip addr add 0.0.0.4/0 scope 0x40 secondary dev bond0
ip addr del 4.117.174.103/0 scope 0x40 dev bond0
ip link delete bond0 type bond

In this reproduction test case, an incorrect 'last_prim' is found in
__inet_del_ifa(), as a result, the secondary address(0.0.0.4/0 scope 0x40)
is lost. The memory of the secondary address is leaked and the reference of
in_device and net_device is leaked.

Fix this problem:
Look for 'last_prim' starting at location of the deleted IP and inserting
the promoted IP into the location of 'last_prim'.
Comment 1 Alexander B 2025-12-25 12:14:07 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122425-CVE-2023-53995-1860@gregkh/T