Seems like it's fixed by this commit:
commit 542fbda0f08f1cbbc250f9e59f7537649651d0c8
Author: Florian Westphal <[email protected]>
Date: Tue Dec 11 07:45:29 2018 +0100
netfilter: nat: can't use dst_hold on noref dst
The dst entry might already have a zero refcount, waiting on rcu list
to be free'd. Using dst_hold() transitions its reference count to 1, and
next dst release will try to free it again -- resulting in a double free:
WARNING: CPU: 1 PID: 0 at include/net/dst.h:239
nf_xfrm_me_harder+0xe7/0x130 [nf_nat]
RIP: 0010:nf_xfrm_me_harder+0xe7/0x130 [nf_nat]
Code: 48 8b 5c 24 60 65 48 33 1c 25 28 00 00 00 75 53 48 83 c4 68 5b 5d
41 5c c3 85 c0 74 0d 8d 48 01 f0 0f b1 0a 74 86 85 c0 75 f3 <0f> 0b e9 7b ff ff
ff 29 c6 31 d2 b9 20 00 48 00 4c 89 e7 e8 31 27
Call Trace:
nf_nat_ipv4_out+0x78/0x90 [nf_nat_ipv4]
nf_hook_slow+0x36/0xd0
ip_output+0x9f/0xd0
ip_forward+0x328/0x440
ip_rcv+0x8a/0xb0
Use dst_hold_safe instead and bail out if we cannot take a reference.
Fixes: a4c2fd7f7891 ("net: remove DST_NOCACHE flag")
Reported-by: Martin Zaharinov <[email protected]>
Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
Try kernel >= v4.20 to verify.
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https://bugs.launchpad.net/bugs/1786752
Title:
Reference counter issue in 4.15 (nf_xfrm_me_harder / dst_release)
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