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srcu: Tighten cleanup_srcu_struct() GP checks

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Currently, cleanup_srcu_struct() checks for a grace period in progress,
but it does not check for a grace period that has not yet started but
which might start at any time.  Such a situation could result in a
use-after-free bug, so this commit adds a check for a grace period that
is needed but not yet started to cleanup_srcu_struct().

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2022-01-12 09:52:44 -08:00
parent 3123109284
commit 8ed0076020
1 changed files with 4 additions and 2 deletions
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6
kernel/rcu/srcutree.c
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@ -382,9 +382,11 @@ void cleanup_srcu_struct(struct srcu_struct *ssp)
return; /* Forgot srcu_barrier(), so just leak it! */
}
if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) ||
WARN_ON(rcu_seq_current(&ssp->srcu_gp_seq) != ssp->srcu_gp_seq_needed) ||
WARN_ON(srcu_readers_active(ssp))) {
pr_info("%s: Active srcu_struct %p state: %d\n",
__func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)));
pr_info("%s: Active srcu_struct %p read state: %d gp state: %lu/%lu\n",
__func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)),
rcu_seq_current(&ssp->srcu_gp_seq), ssp->srcu_gp_seq_needed);
return; /* Caller forgot to stop doing call_srcu()? */
}
free_percpu(ssp->sda);