- (djm) [openbsd-compat/bsd-arc4random.c] Fix math bug that caused bias

in arc4random_uniform with upper_bound in (2^30,2*31). Note that
   OpenSSH did not make requests with upper bounds in this range.
This commit is contained in:
Damien Miller 2008-06-04 10:54:00 +10:00
parent a7058ec7c0
commit 58ea61ba2a
2 changed files with 7 additions and 2 deletions

View File

@ -1,3 +1,8 @@
20080604
- (djm) [openbsd-compat/bsd-arc4random.c] Fix math bug that caused bias
in arc4random_uniform with upper_bound in (2^30,2*31). Note that
OpenSSH did not make requests with upper bounds in this range.
20080519
- (djm) [configure.ac mux.c sftp.c openbsd-compat/Makefile.in]
[openbsd-compat/fmt_scaled.c openbsd-compat/openbsd-compat.h]
@ -4023,4 +4028,4 @@
OpenServer 6 and add osr5bigcrypt support so when someone migrates
passwords between UnixWare and OpenServer they will still work. OK dtucker@
$Id: ChangeLog,v 1.4935 2008/05/19 22:57:06 djm Exp $
$Id: ChangeLog,v 1.4936 2008/06/04 00:54:00 djm Exp $

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@ -129,7 +129,7 @@ arc4random_uniform(u_int32_t upper_bound)
min = 1 + ~upper_bound; /* 2**32 - upper_bound */
else {
/* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
min = ((0xffffffff - (upper_bound << 2)) + 1) % upper_bound;
min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
}
#endif