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Change History

In the Linux kernel, the following vulnerability has been resolved:

xfrm: fix refcount leak in xfrm_migrate_policy_find

syzkaller reported a memory leak in xfrm_policy_alloc:

  BUG: memory leak
  unreferenced object 0xffff888114d79000 (size 1024):
    comm "syz.1.17", pid 931
    ...
    xfrm_policy_alloc+0xb3/0x4b0 net/xfrm/xfrm_policy.c:432

The root cause is a double call to xfrm_pol_hold_rcu() in
xfrm_migrate_policy_find(). The lookup function already returns
a policy with held reference, making the second call redundant.

Remove the redundant xfrm_pol_hold_rcu() call to fix the refcount
imbalance and prevent the memory leak.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

https://git.kernel.org/stable/c/21e235a36cfb6d145cefb10728f12f5dc5412f54

https://git.kernel.org/stable/c/70c2a89a3bc207c3bfbf6f21bb439809e0a4a27a

https://git.kernel.org/stable/c/83317cce60a032c49480dcdabe146435bd689d03

https://git.kernel.org/stable/c/836ee1b0426ea3db31531e9581cc32f513d24e32