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srcu: Take early exit on memory-allocation failure

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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@ozlabs.ru/
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-09-10 11:54:42 -07:00
parent 56292e8609
commit 50edb98853
1 changed files with 3 additions and 1 deletions
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4
kernel/rcu/srcutree.c
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@ -177,11 +177,13 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
INIT_DELAYED_WORK(&ssp->work, process_srcu); INIT_DELAYED_WORK(&ssp->work, process_srcu);
if (!is_static) if (!is_static)
ssp->sda = alloc_percpu(struct srcu_data); ssp->sda = alloc_percpu(struct srcu_data);
if (!ssp->sda)
return -ENOMEM;
init_srcu_struct_nodes(ssp, is_static); init_srcu_struct_nodes(ssp, is_static);
ssp->srcu_gp_seq_needed_exp = 0; ssp->srcu_gp_seq_needed_exp = 0;
ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); ssp->srcu_last_gp_end = ktime_get_mono_fast_ns();
smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */ smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */
return ssp->sda ? 0 : -ENOMEM; return 0;
} }
#ifdef CONFIG_DEBUG_LOCK_ALLOC #ifdef CONFIG_DEBUG_LOCK_ALLOC