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| author | Frederic Weisbecker <frederic@kernel.org> | 2021-06-28 16:34:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-08-12 14:22:16 +0300 |
| commit | f08b2d078cbb9a0561b85ceb6a07b670c84e1a04 (patch) | |
| tree | 54ca4ae25ff6b1a415ec6989e7471906a8845b32 /include | |
| parent | 23e36a8610ca4db5726c6e89910857c9fe3ac997 (diff) | |
| download | linux-f08b2d078cbb9a0561b85ceb6a07b670c84e1a04.tar.xz | |
xfrm: Fix RCU vs hash_resize_mutex lock inversion
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: 77cc278f7b20 (xfrm: policy: Use sequence counters with associated lock)
Cc: stable@vger.kernel.org
Cc: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Varad Gautam <varad.gautam@suse.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/netns/xfrm.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h index b59d73d529ba..22e1bc72b979 100644 --- a/include/net/netns/xfrm.h +++ b/include/net/netns/xfrm.h @@ -74,6 +74,7 @@ struct netns_xfrm { #endif spinlock_t xfrm_state_lock; seqcount_t xfrm_state_hash_generation; + seqcount_spinlock_t xfrm_policy_hash_generation; spinlock_t xfrm_policy_lock; struct mutex xfrm_cfg_mutex; |