f08b2d078c
commit 2580d3f40022642452dd8422bfb8c22e54cf84bb upstream.
xfrm_bydst_resize() calls synchronize_rcu() while holding
hash_resize_mutex. But then on PREEMPT_RT configurations,
xfrm_policy_lookup_bytype() may acquire that mutex while running in an
RCU read side critical section. This results in a deadlock.
In fact the scope of hash_resize_mutex is way beyond the purpose of
xfrm_policy_lookup_bytype() to just fetch a coherent and stable policy
for a given destination/direction, along with other details.
The lower level net->xfrm.xfrm_policy_lock, which among other things
protects per destination/direction references to policy entries, is
enough to serialize and benefit from priority inheritance against the
write side. As a bonus, it makes it officially a per network namespace
synchronization business where a policy table resize on namespace A
shouldn't block a policy lookup on namespace B.
Fixes:
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||
|---|---|---|
| .. | ||
| bpf.h | ||
| can.h | ||
| conntrack.h | ||
| core.h | ||
| dccp.h | ||
| generic.h | ||
| hash.h | ||
| ieee802154_6lowpan.h | ||
| ipv4.h | ||
| ipv6.h | ||
| mib.h | ||
| mpls.h | ||
| netfilter.h | ||
| nexthop.h | ||
| nftables.h | ||
| packet.h | ||
| sctp.h | ||
| unix.h | ||
| x_tables.h | ||
| xdp.h | ||
| xfrm.h | ||