Commit d327ea15 authored by Richard Fitzgerald's avatar Richard Fitzgerald Committed by Petr Mladek
Browse files

random32: Fix implicit truncation warning in prandom_seed_state() 



sparse generates the following warning:

 include/linux/prandom.h:114:45: sparse: sparse: cast truncates bits from
 constant value

This is because the 64-bit seed value is manipulated and then placed in a
u32, causing an implicit cast and truncation. A forced cast to u32 doesn't
prevent this warning, which is reasonable because a typecast doesn't prove
that truncation was expected.

Logical-AND the value with 0xffffffff to make explicit that truncation to
32-bit is intended.

Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarRichard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210525122012.6336-3-rf@opensource.cirrus.com
parent 1b932689

include/linux/prandom.h

+1 −1
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ static inline u32 __seed(u32 x, u32 m) 
 */

static inline void prandom_seed_state(struct rnd_state *state, u64 seed)

{

	u32 i = (seed >> 32) ^ (seed << 10) ^ seed;

	u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;



	state->s1 = __seed(i,   2U);

	state->s2 = __seed(i,   8U);