Commit 2a530080 authored by Rusty Russell's avatar Rusty Russell

cpumask: zero extra bits in alloc_cpumask_var_node

Impact: extra safety checks during transition

When CONFIG_CPUMASKS_OFFSTACK is set, the new cpumask_ operators only
use bits up to nr_cpu_ids, not NR_CPUS.  Using the old cpus_ operators
on these masks can mean accessing undefined bits.

After some discussion, Mike and I decided to err on the side of caution;
we zero the "undefined" bits in alloc_cpumask_var_node() until all the
old cpumask functions are removed.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 5db0e1e9
...@@ -107,6 +107,14 @@ bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) ...@@ -107,6 +107,14 @@ bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
dump_stack(); dump_stack();
} }
#endif #endif
/* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
if (*mask) {
unsigned int tail;
tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
memset(cpumask_bits(*mask) + cpumask_size() - tail,
0, tail);
}
return *mask != NULL; return *mask != NULL;
} }
EXPORT_SYMBOL(alloc_cpumask_var_node); EXPORT_SYMBOL(alloc_cpumask_var_node);
......
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