treewide: use get_random_{u8,u16}() when possible, part 1

Rather than truncate a 32-bit value to a 16-bit value or an 8-bit value,
simply use the get_random_{u8,u16}() functions, which are faster than
wasting the additional bytes from a 32-bit value. This was done
mechanically with this coccinelle script:

@@
expression E;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
typedef __be16;
typedef __le16;
typedef u8;
@@
(
- (get_random_u32() & 0xffff)
+ get_random_u16()
|
- (get_random_u32() & 0xff)
+ get_random_u8()
|
- (get_random_u32() % 65536)
+ get_random_u16()
|
- (get_random_u32() % 256)
+ get_random_u8()
|
- (get_random_u32() >> 16)
+ get_random_u16()
|
- (get_random_u32() >> 24)
+ get_random_u8()
|
- (u16)get_random_u32()
+ get_random_u16()
|
- (u8)get_random_u32()
+ get_random_u8()
|
- (__be16)get_random_u32()
+ (__be16)get_random_u16()
|
- (__le16)get_random_u32()
+ (__le16)get_random_u16()
|
- prandom_u32_max(65536)
+ get_random_u16()
|
- prandom_u32_max(256)
+ get_random_u8()
|
- E->inet_id = get_random_u32()
+ E->inet_id = get_random_u16()
)

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
identifier v;
@@
- u16 v = get_random_u32();
+ u16 v = get_random_u16();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u8;
identifier v;
@@
- u8 v = get_random_u32();
+ u8 v = get_random_u8();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
u16 v;
@@
-  v = get_random_u32();
+  v = get_random_u16();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u8;
u8 v;
@@
-  v = get_random_u32();
+  v = get_random_u8();

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Examine limits
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value < 256:
        coccinelle.RESULT = cocci.make_ident("get_random_u8")
elif value < 65536:
        coccinelle.RESULT = cocci.make_ident("get_random_u16")
else:
        print("Skipping large mask of %s" % (literal))
        cocci.include_match(False)

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
identifier add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       (RESULT() & LITERAL)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> # for sch_cake
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

6 files changed, 7 insertions, 7 deletions

diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
index f90bfba4b303..eda129d0143e 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -1466,7 +1466,7 @@ static void make_established(struct sock *sk, u32 snd_isn, unsigned int opt)
 	tp->write_seq = snd_isn;
 	tp->snd_nxt = snd_isn;
 	tp->snd_una = snd_isn;
-	inet_sk(sk)->inet_id = prandom_u32();
+	inet_sk(sk)->inet_id = get_random_u16();
 	assign_rxopt(sk, opt);
 
 	if (tp->rcv_wnd > (RCV_BUFSIZ_M << 10))
diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 7df78a721b04..791b4a53d69f 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -438,7 +438,7 @@ static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
 			if ((--bc->hdlctx.slotcnt) > 0)
 				return 0;
 			bc->hdlctx.slotcnt = bc->ch_params.slottime;
-			if (prandom_u32_max(256) > bc->ch_params.ppersist)
+			if (get_random_u8() > bc->ch_params.ppersist)
 				return 0;
 		}
 	}
diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index bef904325a0f..2263029d1a20 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -377,7 +377,7 @@ void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
 	if ((--s->hdlctx.slotcnt) > 0)
 		return;
 	s->hdlctx.slotcnt = s->ch_params.slottime;
-	if (prandom_u32_max(256) > s->ch_params.ppersist)
+	if (get_random_u8() > s->ch_params.ppersist)
 		return;
 	start_tx(dev, s);
 }
diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 97a6cc5c7ae8..2ed2f836f09a 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -626,7 +626,7 @@ static void yam_arbitrate(struct net_device *dev)
 	yp->slotcnt = yp->slot / 10;
 
 	/* is random > persist ? */
-	if (prandom_u32_max(256) > yp->pers)
+	if (get_random_u8() > yp->pers)
 		return;
 
 	yam_start_tx(dev, yp);
diff --git a/drivers/net/wireguard/selftest/allowedips.c b/drivers/net/wireguard/selftest/allowedips.c
index 41db10f9be49..dd897c0740a2 100644
--- a/drivers/net/wireguard/selftest/allowedips.c
+++ b/drivers/net/wireguard/selftest/allowedips.c
@@ -310,7 +310,7 @@ static __init bool randomized_test(void)
 			for (k = 0; k < 4; ++k)
 				mutated[k] = (mutated[k] & mutate_mask[k]) |
 					     (~mutate_mask[k] &
-					      prandom_u32_max(256));
+					      get_random_u8());
 			cidr = prandom_u32_max(32) + 1;
 			peer = peers[prandom_u32_max(NUM_PEERS)];
 			if (wg_allowedips_insert_v4(&t,
@@ -354,7 +354,7 @@ static __init bool randomized_test(void)
 			for (k = 0; k < 4; ++k)
 				mutated[k] = (mutated[k] & mutate_mask[k]) |
 					     (~mutate_mask[k] &
-					      prandom_u32_max(256));
+					      get_random_u8());
 			cidr = prandom_u32_max(128) + 1;
 			peer = peers[prandom_u32_max(NUM_PEERS)];
 			if (wg_allowedips_insert_v6(&t,
diff --git a/drivers/net/wireless/st/cw1200/wsm.c b/drivers/net/wireless/st/cw1200/wsm.c
index 5a3e7a626702..4a9e4b5d3547 100644
--- a/drivers/net/wireless/st/cw1200/wsm.c
+++ b/drivers/net/wireless/st/cw1200/wsm.c
@@ -1594,7 +1594,7 @@ static int cw1200_get_prio_queue(struct cw1200_common *priv,
 		edca = &priv->edca.params[i];
 		score = ((edca->aifns + edca->cwmin) << 16) +
 			((edca->cwmax - edca->cwmin) *
-			 (get_random_int() & 0xFFFF));
+			 get_random_u16());
 		if (score < best && (winner < 0 || i != 3)) {
 			best = score;
 			winner = i;