random: silence compiler warnings and fix race
Odd versions of gcc for the sh4 architecture will actually warn about
flags being used while uninitialized, so we set them to zero. Non crazy
gccs will optimize that out again, so it doesn't make a difference.
Next, over aggressive gccs could inline the expression that defines
use_lock, which could then introduce a race resulting in a lock
imbalance. By using READ_ONCE, we prevent that fate. Finally, we make
that assignment const, so that gcc can still optimize a nice amount.
Finally, we fix a potential deadlock between primary_crng.lock and
batched_entropy_reset_lock, where they could be called in opposite
order. Moving the call to invalidate_batched_entropy to outside the lock
rectifies this issue.
Fixes: b169c13de4
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
parent
b169c13de4
commit
4a072c71f4
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@ -803,13 +803,13 @@ static int crng_fast_load(const char *cp, size_t len)
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p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
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p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
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cp++; crng_init_cnt++; len--;
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cp++; crng_init_cnt++; len--;
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}
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}
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spin_unlock_irqrestore(&primary_crng.lock, flags);
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if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
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if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
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invalidate_batched_entropy();
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invalidate_batched_entropy();
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crng_init = 1;
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crng_init = 1;
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wake_up_interruptible(&crng_init_wait);
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wake_up_interruptible(&crng_init_wait);
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pr_notice("random: fast init done\n");
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pr_notice("random: fast init done\n");
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}
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}
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spin_unlock_irqrestore(&primary_crng.lock, flags);
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return 1;
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return 1;
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}
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}
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@ -841,6 +841,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
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}
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}
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memzero_explicit(&buf, sizeof(buf));
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memzero_explicit(&buf, sizeof(buf));
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crng->init_time = jiffies;
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crng->init_time = jiffies;
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spin_unlock_irqrestore(&primary_crng.lock, flags);
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if (crng == &primary_crng && crng_init < 2) {
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if (crng == &primary_crng && crng_init < 2) {
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invalidate_batched_entropy();
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invalidate_batched_entropy();
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crng_init = 2;
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crng_init = 2;
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@ -848,7 +849,6 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
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wake_up_interruptible(&crng_init_wait);
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wake_up_interruptible(&crng_init_wait);
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pr_notice("random: crng init done\n");
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pr_notice("random: crng init done\n");
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}
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}
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spin_unlock_irqrestore(&primary_crng.lock, flags);
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}
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}
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static inline void crng_wait_ready(void)
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static inline void crng_wait_ready(void)
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@ -2041,8 +2041,8 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
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u64 get_random_u64(void)
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u64 get_random_u64(void)
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{
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{
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u64 ret;
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u64 ret;
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bool use_lock = crng_init < 2;
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bool use_lock = READ_ONCE(crng_init) < 2;
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unsigned long flags;
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unsigned long flags = 0;
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struct batched_entropy *batch;
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struct batched_entropy *batch;
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#if BITS_PER_LONG == 64
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#if BITS_PER_LONG == 64
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@ -2073,8 +2073,8 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
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u32 get_random_u32(void)
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u32 get_random_u32(void)
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{
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{
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u32 ret;
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u32 ret;
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bool use_lock = crng_init < 2;
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bool use_lock = READ_ONCE(crng_init) < 2;
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unsigned long flags;
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unsigned long flags = 0;
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struct batched_entropy *batch;
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struct batched_entropy *batch;
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if (arch_get_random_int(&ret))
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if (arch_get_random_int(&ret))
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