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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-17 14:23:14 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-17 14:23:14 -1000
commit5ee22beeb25a5fa7fc6daf3597a8d9265f8c9ce1 (patch)
tree209058ef31be54ecdd8a023ed3fb531c3a939d33 /drivers/char/random.c
parent5cfb277d660b8b285fc831701e91f01ec933c7b4 (diff)
parente33ba5fa7afce1a9f159704121d4e4d110df8185 (diff)
downloadleg-kernel-5ee22beeb25a5fa7fc6daf3597a8d9265f8c9ce1.tar.gz
Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random
Pull randomness bugfix from Ted Ts'o: "random: fix entropy accounting bug introduced in v3.15" * tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: random: fix nasty entropy accounting bug
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 4ad71ef2cd59..0a7ac0a7b252 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -980,7 +980,6 @@ static void push_to_pool(struct work_struct *work)
static size_t account(struct entropy_store *r, size_t nbytes, int min,
int reserved)
{
- int have_bytes;
int entropy_count, orig;
size_t ibytes;
@@ -989,17 +988,19 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
/* Can we pull enough? */
retry:
entropy_count = orig = ACCESS_ONCE(r->entropy_count);
- have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
ibytes = nbytes;
/* If limited, never pull more than available */
- if (r->limit)
- ibytes = min_t(size_t, ibytes, have_bytes - reserved);
+ if (r->limit) {
+ int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
+
+ if ((have_bytes -= reserved) < 0)
+ have_bytes = 0;
+ ibytes = min_t(size_t, ibytes, have_bytes);
+ }
if (ibytes < min)
ibytes = 0;
- if (have_bytes >= ibytes + reserved)
- entropy_count -= ibytes << (ENTROPY_SHIFT + 3);
- else
- entropy_count = reserved << (ENTROPY_SHIFT + 3);
+ if ((entropy_count -= ibytes << (ENTROPY_SHIFT + 3)) < 0)
+ entropy_count = 0;
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
goto retry;