CVE-2021-47555 (GCVE-0-2021-47555)
Vulnerability from cvelistv5
Published
2024-05-24 15:09
Modified
2025-05-04 12:41
Severity ?
4.4 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L
Summary
In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix underflow for the real_dev refcnt Inject error before dev_hold(real_dev) in register_vlan_dev(), and execute the following testcase: ip link add dev dummy1 type dummy ip link add name dummy1.100 link dummy1 type vlan id 100 ip link del dev dummy1 When the dummy netdevice is removed, we will get a WARNING as following: ======================================================================= refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 2 PID: 0 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 and an endless loop of: ======================================================================= unregister_netdevice: waiting for dummy1 to become free. Usage count = -1073741824 That is because dev_put(real_dev) in vlan_dev_free() be called without dev_hold(real_dev) in register_vlan_dev(). It makes the refcnt of real_dev underflow. Move the dev_hold(real_dev) to vlan_dev_init() which is the call-back of ndo_init(). That makes dev_hold() and dev_put() for vlan's real_dev symmetrical.
References
Impacted products
Vendor Product Version
Linux Linux Version: 700602b662d7eaa816b1a3cb0abe7a85de358fd4
Version: e04a7a84bb77f9cdf4475340fe931389bc72331c
Version: 21032425c36ff85f16e72ca92193a8c401e4acd5
Version: 563bcbae3ba233c275c244bfce2efe12938f5363
Version: fca96b3f852a1b369b7b2844ce357cd689879934
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   Linux Linux Version: 5.4.160   ≤
Version: 5.10.80   ≤
Version: 5.15.3   ≤
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