Fix a BUG splat found by trinity.

-----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2
 
 iQIcBAABCAAGBQJTygXeAAoJENNvdpvBGATwBVYP/3OHIb58JhHjC/GbHKhe0UdX
 eSBle+8bcDdwADXBQ2Slzp7bVBwBHaEgKOz0Y9iTObrICb5orUGtB7MmGi9b9WIW
 8igTkvNhQxwNZat89U5SOpPuwSJEyR9LeIKN8JG75j+ymX/H1vjsojJcXxfZzYT0
 qoiUs32VbmglfVPy1WvPLZ/0fYtaRwzE6des7yzZHYbEvgX5JIJ7m4sQftMj4a+L
 CNiLHXLijsUX9CG94Gjw7R7/PLK83UNM+ER5zUTIC6EqRJCZVIQAU0zvyE5sm3ZK
 v3n8aJypZZhNBGJm4SNWlwsbwllx9BvPOq2DadY+/Jpzqrxy1saYB+XoKKdT3t2Y
 3OJb/eh02wuCzCzJgNNP9CJhdPV7h4qrg5M1OqrBsFgXEAlISLvWEM+//FB8Hsmv
 NDKeWl6Y5Iy6UCZDVQpuYCJTo46ACt0DBLpOE9tXDtz6yuLF+Hs3GmRPz368EcEy
 t98UmU7mS447FQdqjThKdH1g/ZeGepXDMkk/hosmnck7OgQzuLMBnAagwouQ9YSH
 O32MyvGHkAPEL2SB2WzGdWIHr/K2EWiyAoO3OVaUrJ7tVrGvVig/WsgYyNaHzBlp
 5VRCdBXJ78tH+KYl0lIkrzrOnd1AegQtIIH5E3iZsdUVqCM/DdDd5ewwWxC7Ar3s
 PGrT4lp8vqIT0H3D65a5
 =8rgT
 -----END PGP SIGNATURE-----

Merge tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull /dev/random fix from Ted Ts'o:
 "Fix a BUG splat found by trinity"

* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: check for increase of entropy_count because of signed conversion
This commit is contained in:
Linus Torvalds 2014-07-18 20:26:46 -10:00
commit b8d2d12804

View File

@ -641,7 +641,7 @@ retry:
} while (unlikely(entropy_count < pool_size-2 && pnfrac));
}
if (entropy_count < 0) {
if (unlikely(entropy_count < 0)) {
pr_warn("random: negative entropy/overflow: pool %s count %d\n",
r->name, entropy_count);
WARN_ON(1);
@ -981,7 +981,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
int reserved)
{
int entropy_count, orig;
size_t ibytes;
size_t ibytes, nfrac;
BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
@ -999,7 +999,17 @@ retry:
}
if (ibytes < min)
ibytes = 0;
if ((entropy_count -= ibytes << (ENTROPY_SHIFT + 3)) < 0)
if (unlikely(entropy_count < 0)) {
pr_warn("random: negative entropy count: pool %s count %d\n",
r->name, entropy_count);
WARN_ON(1);
entropy_count = 0;
}
nfrac = ibytes << (ENTROPY_SHIFT + 3);
if ((size_t) entropy_count > nfrac)
entropy_count -= nfrac;
else
entropy_count = 0;
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
@ -1376,6 +1386,7 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
"with %d bits of entropy available\n",
current->comm, nonblocking_pool.entropy_total);
nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),