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Commit d76758c7 authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by Greg Kroah-Hartman
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random: do not sign extend bytes for rotation when mixing 



commit 0d9488ffbf2faddebc6bac055bfa6c93b94056a3 upstream.

By using `char` instead of `unsigned char`, certain platforms will sign
extend the byte when `w = rol32(*bytes++, input_rotate)` is called,
meaning that bit 7 is overrepresented when mixing. This isn't a real
problem (unless the mixer itself is already broken) since it's still
invertible, but it's not quite correct either. Fix this by using an
explicit unsigned type.

Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c2f0a89c

drivers/char/random.c

+1 −1
Original line number Diff line number Diff line
@@ -548,7 +548,7 @@ static void _mix_pool_bytes(struct entropy_store *r, const void *in, 
	unsigned long i, tap1, tap2, tap3, tap4, tap5;

	int input_rotate;

	int wordmask = r->poolinfo->poolwords - 1;

	const char *bytes = in;

	const unsigned char *bytes = in;

	__u32 w;



	tap1 = r->poolinfo->tap1;