The following commit has been merged into the core/rcu branch of tip: Commit-ID: 50edb988534c621a56ca103c0c16ac59e7399f01 Gitweb: https://git.kernel.org/tip/50edb988534c621a56ca103c0c16ac59e7399f01 Author: Paul E. McKenney <paulmck@xxxxxxxxxx> AuthorDate: Thu, 10 Sep 2020 11:54:42 -07:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> CommitterDate: Thu, 19 Nov 2020 19:37:17 -08:00 srcu: Take early exit on memory-allocation failure It turns out that init_srcu_struct() can be invoked from usermode tasks, and that fatal signals received by these tasks can cause memory-allocation failures. These failures are not handled well by init_srcu_struct(), so much so that NULL pointer dereferences can result. This commit therefore causes init_srcu_struct() to take an early exit upon detection of memory-allocation failure. Link: https://lore.kernel.org/lkml/20200908144306.33355-1-aik@xxxxxxxxx/ Reported-by: Alexey Kardashevskiy <aik@xxxxxxxxx> Tested-by: Alexey Kardashevskiy <aik@xxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/srcutree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index c13348e..6f7880a 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -177,11 +177,13 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) INIT_DELAYED_WORK(&ssp->work, process_srcu); if (!is_static) ssp->sda = alloc_percpu(struct srcu_data); + if (!ssp->sda) + return -ENOMEM; init_srcu_struct_nodes(ssp, is_static); ssp->srcu_gp_seq_needed_exp = 0; ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */ - return ssp->sda ? 0 : -ENOMEM; + return 0; } #ifdef CONFIG_DEBUG_LOCK_ALLOC
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