| Message ID | 20180413013046.404-3-tytso@mit.edu (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
Hi Theodore,
I love your patch! Perhaps something to improve:
[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v4.16 next-20180413]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Theodore-Ts-o/random-fix-crng_ready-test/20180414-055120
config: i386-randconfig-x014-201814 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
drivers/char/random.c: In function 'numa_crng_init':
>> drivers/char/random.c:813:1: warning: no return statement in function returning non-void [-Wreturn-type]
static int numa_crng_init(void) {}
^~~~~~
vim +813 drivers/char/random.c
789
790 #ifdef CONFIG_NUMA
791 static void numa_crng_init(void)
792 {
793 int i;
794 struct crng_state *crng;
795 struct crng_state **pool;
796
797 pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
798 for_each_online_node(i) {
799 crng = kmalloc_node(sizeof(struct crng_state),
800 GFP_KERNEL | __GFP_NOFAIL, i);
801 spin_lock_init(&crng->lock);
802 crng_initialize(crng);
803 pool[i] = crng;
804 }
805 mb();
806 if (cmpxchg(&crng_node_pool, NULL, pool)) {
807 for_each_node(i)
808 kfree(pool[i]);
809 kfree(pool);
810 }
811 }
812 #else
> 813 static int numa_crng_init(void) {}
814 #endif
815
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/drivers/char/random.c b/drivers/char/random.c index 2154a5fe4c81..681ee0c0de24 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -787,6 +787,32 @@ static void crng_initialize(struct crng_state *crng) crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; } +#ifdef CONFIG_NUMA +static void numa_crng_init(void) +{ + int i; + struct crng_state *crng; + struct crng_state **pool; + + pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); + for_each_online_node(i) { + crng = kmalloc_node(sizeof(struct crng_state), + GFP_KERNEL | __GFP_NOFAIL, i); + spin_lock_init(&crng->lock); + crng_initialize(crng); + pool[i] = crng; + } + mb(); + if (cmpxchg(&crng_node_pool, NULL, pool)) { + for_each_node(i) + kfree(pool[i]); + kfree(pool); + } +} +#else +static int numa_crng_init(void) {} +#endif + /* * crng_fast_load() can be called by code in the interrupt service * path. So we can't afford to dilly-dally. @@ -893,6 +919,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) spin_unlock_irqrestore(&primary_crng.lock, flags); if (crng == &primary_crng && crng_init < 2) { invalidate_batched_entropy(); + numa_crng_init(); crng_init = 2; process_random_ready_list(); wake_up_interruptible(&crng_init_wait); @@ -1727,28 +1754,9 @@ static void init_std_data(struct entropy_store *r) */ static int rand_initialize(void) { -#ifdef CONFIG_NUMA - int i; - struct crng_state *crng; - struct crng_state **pool; -#endif - init_std_data(&input_pool); init_std_data(&blocking_pool); crng_initialize(&primary_crng); - -#ifdef CONFIG_NUMA - pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); - for_each_online_node(i) { - crng = kmalloc_node(sizeof(struct crng_state), - GFP_KERNEL | __GFP_NOFAIL, i); - spin_lock_init(&crng->lock); - crng_initialize(crng); - pool[i] = crng; - } - mb(); - crng_node_pool = pool; -#endif return 0; } early_initcall(rand_initialize);
Until the primary_crng is fully initialized, don't initialize the NUMA crng nodes. Otherwise users of /dev/urandom on NUMA systems before the CRNG is fully initialized can get very bad quality randomness. Of course everyone should move to getrandom(2) where this won't be an issue, but there's a lot of legacy code out there. Reported-by: Jann Horn <jannh@google.com> Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...") Cc: stable@kernel.org # 4.8+ Signed-off-by: Theodore Ts'o <tytso@mit.edu> --- drivers/char/random.c | 46 +++++++++++++++++++++++++++------------------- 1 file changed, 27 insertions(+), 19 deletions(-)