[PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jason A. Donenfeld]

Hey everyone,

Here's the second and final tranche of tree-wide conversions to get
random integer handling a bit tamer. It's predominantly another
Coccinelle-based patchset.

First we s/prandom_u32_max/get_random_u32_below/, since the former is
just a deprecated alias for the latter. Then in the next commit we can
remove prandom_u32_max all together. I'm quite happy about finally being
able to do that. It means that prandom.h is now only for deterministic and 
repeatable randomness, not non-deterministic/cryptographic randomness.
That line is no longer blurred.

Then, in order to clean up a bunch of inefficient patterns, we introduce
two trivial static inline helper functions built on top of
get_random_u32_below: get_random_u32_above and get_random_u32_between.
These are pretty straight forward to use and understand. Then the final
two patches convert some gnarly open-coded number juggling to use these
helpers.

I've used Coccinelle for all the treewide patches, so hopefully review
is rather uneventful. I didn't accept all of the changes that Coccinelle
proposed, though, as these tend to be somewhat context-specific. I erred
on the side of just going with the most obvious cases, at least this
time through. And then we can address more complicated cases through
actual maintainer trees.

Since get_random_u32_below() sits in my random.git tree, these patches
too will flow through that same tree.

Regards,
Jason

Cc: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Helge Deller <deller@gmx.de>
Cc: netdev@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: loongarch@lists.linux.dev
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mmc@vger.kernel.org
Cc: linux-parisc@vger.kernel.org

Jason A. Donenfeld (5):
  treewide: use get_random_u32_below() instead of deprecated function
  prandom: remove prandom_u32_max()
  random: add helpers for random numbers with given floor or range
  treewide: use get_random_u32_{above,below}() instead of manual loop
  treewide: use get_random_u32_between() when possible

 arch/arm/kernel/process.c                     |  2 +-
 arch/arm64/kernel/process.c                   |  2 +-
 arch/loongarch/kernel/process.c               |  2 +-
 arch/loongarch/kernel/vdso.c                  |  2 +-
 arch/mips/kernel/process.c                    |  2 +-
 arch/mips/kernel/vdso.c                       |  2 +-
 arch/parisc/kernel/vdso.c                     |  2 +-
 arch/powerpc/crypto/crc-vpmsum_test.c         |  4 +-
 arch/powerpc/kernel/process.c                 |  2 +-
 arch/s390/kernel/process.c                    |  2 +-
 arch/s390/kernel/vdso.c                       |  2 +-
 arch/sparc/vdso/vma.c                         |  2 +-
 arch/um/kernel/process.c                      |  2 +-
 arch/x86/entry/vdso/vma.c                     |  2 +-
 arch/x86/kernel/module.c                      |  2 +-
 arch/x86/kernel/process.c                     |  2 +-
 arch/x86/mm/pat/cpa-test.c                    |  4 +-
 crypto/rsa-pkcs1pad.c                         |  2 +-
 crypto/testmgr.c                              | 86 +++++++++----------
 drivers/block/drbd/drbd_receiver.c            |  4 +-
 drivers/bus/mhi/host/internal.h               |  2 +-
 drivers/dma-buf/st-dma-fence-chain.c          |  6 +-
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |  2 +-
 .../drm/i915/gt/intel_execlists_submission.c  |  2 +-
 drivers/gpu/drm/i915/intel_memory_region.c    |  4 +-
 drivers/infiniband/core/cma.c                 |  2 +-
 drivers/infiniband/hw/cxgb4/id_table.c        |  4 +-
 drivers/infiniband/hw/hns/hns_roce_ah.c       |  5 +-
 drivers/infiniband/ulp/rtrs/rtrs-clt.c        |  2 +-
 drivers/md/bcache/request.c                   |  2 +-
 drivers/media/common/v4l2-tpg/v4l2-tpg-core.c |  8 +-
 .../media/test-drivers/vidtv/vidtv_demod.c    |  8 +-
 .../test-drivers/vivid/vivid-kthread-cap.c    |  2 +-
 .../test-drivers/vivid/vivid-kthread-out.c    |  2 +-
 .../media/test-drivers/vivid/vivid-radio-rx.c |  4 +-
 .../media/test-drivers/vivid/vivid-sdr-cap.c  |  2 +-
 .../test-drivers/vivid/vivid-touch-cap.c      |  2 +-
 drivers/mmc/core/core.c                       |  4 +-
 drivers/mmc/host/dw_mmc.c                     |  2 +-
 drivers/mtd/nand/raw/nandsim.c                |  4 +-
 drivers/mtd/tests/mtd_nandecctest.c           | 10 +--
 drivers/mtd/tests/stresstest.c                |  8 +-
 drivers/mtd/ubi/debug.c                       |  2 +-
 drivers/mtd/ubi/debug.h                       |  6 +-
 drivers/net/ethernet/broadcom/cnic.c          |  2 +-
 .../chelsio/inline_crypto/chtls/chtls_io.c    |  4 +-
 drivers/net/phy/at803x.c                      |  2 +-
 drivers/net/team/team_mode_random.c           |  2 +-
 drivers/net/wireguard/selftest/allowedips.c   | 20 ++---
 drivers/net/wireguard/timers.c                |  4 +-
 .../broadcom/brcm80211/brcmfmac/p2p.c         |  2 +-
 .../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c |  2 +-
 drivers/pci/p2pdma.c                          |  2 +-
 drivers/s390/scsi/zfcp_fc.c                   |  2 +-
 drivers/scsi/fcoe/fcoe_ctlr.c                 |  4 +-
 drivers/scsi/qedi/qedi_main.c                 |  2 +-
 drivers/scsi/scsi_debug.c                     |  6 +-
 fs/ceph/inode.c                               |  2 +-
 fs/ceph/mdsmap.c                              |  2 +-
 fs/ext2/ialloc.c                              |  2 +-
 fs/ext4/ialloc.c                              |  2 +-
 fs/ext4/mmp.c                                 |  8 +-
 fs/ext4/super.c                               |  5 +-
 fs/f2fs/gc.c                                  |  2 +-
 fs/f2fs/segment.c                             |  8 +-
 fs/ubifs/debug.c                              |  8 +-
 fs/ubifs/lpt_commit.c                         | 14 +--
 fs/ubifs/tnc_commit.c                         |  2 +-
 fs/xfs/libxfs/xfs_alloc.c                     |  2 +-
 fs/xfs/libxfs/xfs_ialloc.c                    |  2 +-
 fs/xfs/xfs_error.c                            |  2 +-
 include/linux/damon.h                         |  2 +-
 include/linux/nodemask.h                      |  2 +-
 include/linux/prandom.h                       |  6 --
 include/linux/random.h                        | 24 ++++++
 kernel/bpf/core.c                             |  4 +-
 kernel/kcsan/selftest.c                       |  4 +-
 kernel/locking/test-ww_mutex.c                |  4 +-
 kernel/time/clocksource.c                     |  2 +-
 lib/fault-inject.c                            |  2 +-
 lib/find_bit_benchmark.c                      |  4 +-
 lib/kobject.c                                 |  2 +-
 lib/reed_solomon/test_rslib.c                 |  6 +-
 lib/sbitmap.c                                 |  4 +-
 lib/test-string_helpers.c                     |  2 +-
 lib/test_fprobe.c                             |  5 +-
 lib/test_hexdump.c                            | 10 +--
 lib/test_kprobes.c                            |  5 +-
 lib/test_list_sort.c                          |  2 +-
 lib/test_printf.c                             |  2 +-
 lib/test_rhashtable.c                         |  4 +-
 lib/test_vmalloc.c                            |  8 +-
 mm/kasan/kasan_test.c                         |  6 +-
 mm/kfence/core.c                              |  4 +-
 mm/kfence/kfence_test.c                       |  4 +-
 mm/slub.c                                     |  2 +-
 mm/swapfile.c                                 |  5 +-
 net/802/garp.c                                |  2 +-
 net/802/mrp.c                                 |  2 +-
 net/batman-adv/bat_iv_ogm.c                   |  4 +-
 net/batman-adv/bat_v_elp.c                    |  2 +-
 net/batman-adv/bat_v_ogm.c                    |  4 +-
 net/batman-adv/network-coding.c               |  2 +-
 net/bluetooth/mgmt.c                          |  5 +-
 net/can/j1939/socket.c                        |  2 +-
 net/can/j1939/transport.c                     |  2 +-
 net/ceph/mon_client.c                         |  2 +-
 net/ceph/osd_client.c                         |  2 +-
 net/core/neighbour.c                          |  4 +-
 net/core/pktgen.c                             | 37 ++++----
 net/core/stream.c                             |  2 +-
 net/ipv4/icmp.c                               |  2 +-
 net/ipv4/igmp.c                               |  6 +-
 net/ipv4/inet_connection_sock.c               |  2 +-
 net/ipv4/inet_hashtables.c                    |  2 +-
 net/ipv4/route.c                              |  4 +-
 net/ipv4/tcp_bbr.c                            |  2 +-
 net/ipv4/tcp_input.c                          |  3 +-
 net/ipv6/addrconf.c                           |  8 +-
 net/ipv6/mcast.c                              | 10 +--
 net/ipv6/output_core.c                        |  8 +-
 net/ipv6/route.c                              |  2 +-
 net/netfilter/ipvs/ip_vs_twos.c               |  4 +-
 net/netfilter/nf_conntrack_core.c             |  4 +-
 net/netfilter/nf_nat_helper.c                 |  2 +-
 net/netlink/af_netlink.c                      |  2 +-
 net/packet/af_packet.c                        |  4 +-
 net/sched/act_gact.c                          |  2 +-
 net/sched/act_sample.c                        |  2 +-
 net/sched/sch_choke.c                         |  2 +-
 net/sched/sch_netem.c                         |  4 +-
 net/sctp/socket.c                             |  2 +-
 net/sctp/transport.c                          |  2 +-
 net/sunrpc/cache.c                            |  2 +-
 net/sunrpc/xprtsock.c                         |  2 +-
 net/tipc/socket.c                             |  2 +-
 net/vmw_vsock/af_vsock.c                      |  3 +-
 net/xfrm/xfrm_state.c                         |  2 +-
 138 files changed, 309 insertions(+), 318 deletions(-)

-- 
2.38.1

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[PATCH v1 2/5] prandom: remove prandom_u32_max()

[Jason A. Donenfeld]

With no more users left, we can finally remove this function. Its
replacement is get_random_u32_below().

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 include/linux/prandom.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index 1f4a0de7b019..8272c08f3951 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -23,12 +23,6 @@ void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
 #define prandom_init_once(pcpu_state)			\
 	DO_ONCE(prandom_seed_full_state, (pcpu_state))
 
-/* Deprecated: use get_random_u32_below() instead. */
-static inline u32 prandom_u32_max(u32 ep_ro)
-{
-	return get_random_u32_below(ep_ro);
-}
-
 /*
  * Handle minimum values for seeds
  */
-- 
2.38.1


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[PATCH v1 3/5] random: add helpers for random numbers with given floor or range

[Jason A. Donenfeld]

Now that we have get_random_u32_below(), it's trivial to make inline
helpers to compute get_random_u32_above() and get_random_u32_between(),
which will help clean up open coded loops and manual computations
throughout the tree.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 include/linux/random.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/random.h b/include/linux/random.h
index 3a82c0a8bc46..92188a74e50e 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -91,6 +91,30 @@ static inline u32 get_random_u32_below(u32 ceil)
 	}
 }
 
+/*
+ * Returns a random integer in the interval (floor, U32_MAX], with uniform
+ * distribution, suitable for all uses. Fastest when floor is a constant, but
+ * still fast for variable floor as well.
+ */
+static inline u32 get_random_u32_above(u32 floor)
+{
+	BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && floor == U32_MAX,
+			 "get_random_u32_above() must take floor < U32_MAX");
+	return floor + 1 + get_random_u32_below(U32_MAX - floor);
+}
+
+/*
+ * Returns a random integer in the interval [floor, ceil), with uniform
+ * distribution, suitable for all uses. Fastest when floor and ceil are
+ * constant, but still fast for variable floor and ceil as well.
+ */
+static inline u32 get_random_u32_between(u32 floor, u32 ceil)
+{
+	BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && __builtin_constant_p(ceil) &&
+			 floor >= ceil, "get_random_u32_above() must take floor < ceil");
+	return floor + get_random_u32_below(ceil - floor);
+}
+
 /*
  * On 64-bit architectures, protect against non-terminated C string overflows
  * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
-- 
2.38.1


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[PATCH v1 4/5] treewide: use get_random_u32_{above,below}() instead of manual loop

[Jason A. Donenfeld]

These cases were done with this Coccinelle:

@@
expression E;
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (I > E);
+   I = get_random_u32_below(E + 1);

@@
expression E;
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (I >= E);
+   I = get_random_u32_below(E);

@@
expression E;
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (I < E);
+   I = get_random_u32_above(E - 1);

@@
expression E;
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (I <= E);
+   I = get_random_u32_above(E);

@@
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (!I);
+   I = get_random_u32_above(0);

@@
identifier I;
@@
-   do {
      ...
-     I = get_random_u32();
      ...
-   } while (I == 0);
+   I = get_random_u32_above(0);

@@
expression E;
identifier I;
@@
- E + 1 + get_random_u32_below(U32_MAX - E)
+ get_random_u32_above(E)

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 fs/ext4/mmp.c            | 8 +-------
 lib/test_fprobe.c        | 5 +----
 lib/test_kprobes.c       | 5 +----
 net/ipv6/output_core.c   | 8 +-------
 net/vmw_vsock/af_vsock.c | 3 +--
 5 files changed, 5 insertions(+), 24 deletions(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 588cb09c5291..4681fff6665f 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -262,13 +262,7 @@ void ext4_stop_mmpd(struct ext4_sb_info *sbi)
  */
 static unsigned int mmp_new_seq(void)
 {
-	u32 new_seq;
-
-	do {
-		new_seq = get_random_u32();
-	} while (new_seq > EXT4_MMP_SEQ_MAX);
-
-	return new_seq;
+	return get_random_u32_below(EXT4_MMP_SEQ_MAX + 1);
 }
 
 /*
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index e0381b3ec410..1fb56cf5e5ce 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -144,10 +144,7 @@ static unsigned long get_ftrace_location(void *func)
 
 static int fprobe_test_init(struct kunit *test)
 {
-	do {
-		rand1 = get_random_u32();
-	} while (rand1 <= div_factor);
-
+	rand1 = get_random_u32_above(div_factor);
 	target = fprobe_selftest_target;
 	target2 = fprobe_selftest_target2;
 	target_ip = get_ftrace_location(target);
diff --git a/lib/test_kprobes.c b/lib/test_kprobes.c
index eeb1d728d974..1c95e5719802 100644
--- a/lib/test_kprobes.c
+++ b/lib/test_kprobes.c
@@ -339,10 +339,7 @@ static int kprobes_test_init(struct kunit *test)
 	stacktrace_target = kprobe_stacktrace_target;
 	internal_target = kprobe_stacktrace_internal_target;
 	stacktrace_driver = kprobe_stacktrace_driver;
-
-	do {
-		rand1 = get_random_u32();
-	} while (rand1 <= div_factor);
+	rand1 = get_random_u32_above(div_factor);
 	return 0;
 }
 
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 2685c3f15e9d..b5205311f372 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -15,13 +15,7 @@ static u32 __ipv6_select_ident(struct net *net,
 			       const struct in6_addr *dst,
 			       const struct in6_addr *src)
 {
-	u32 id;
-
-	do {
-		id = get_random_u32();
-	} while (!id);
-
-	return id;
+	return get_random_u32_above(0);
 }
 
 /* This function exists only for tap drivers that must support broken
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index f185f57c34e7..9cfed7fd8740 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -626,8 +626,7 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
 	struct sockaddr_vm new_addr;
 
 	if (!port)
-		port = LAST_RESERVED_PORT + 1 +
-			get_random_u32_below(U32_MAX - LAST_RESERVED_PORT);
+		port = get_random_u32_above(LAST_RESERVED_PORT);
 
 	vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);
 
-- 
2.38.1


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[PATCH v1 5/5] treewide: use get_random_u32_between() when possible

[Jason A. Donenfeld]

These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_between(L, H + L)

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/kernel/module.c                      |  2 +-
 crypto/rsa-pkcs1pad.c                         |  2 +-
 crypto/testmgr.c                              | 10 ++++----
 drivers/bus/mhi/host/internal.h               |  2 +-
 drivers/dma-buf/st-dma-fence-chain.c          |  2 +-
 drivers/infiniband/core/cma.c                 |  2 +-
 drivers/infiniband/hw/hns/hns_roce_ah.c       |  5 ++--
 drivers/mtd/nand/raw/nandsim.c                |  2 +-
 drivers/net/wireguard/selftest/allowedips.c   |  8 +++---
 .../broadcom/brcm80211/brcmfmac/p2p.c         |  2 +-
 .../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c |  2 +-
 fs/f2fs/segment.c                             |  6 ++---
 kernel/kcsan/selftest.c                       |  2 +-
 lib/test_hexdump.c                            | 10 ++++----
 lib/test_printf.c                             |  2 +-
 lib/test_vmalloc.c                            |  6 ++---
 mm/kasan/kasan_test.c                         |  6 ++---
 mm/kfence/kfence_test.c                       |  2 +-
 mm/swapfile.c                                 |  5 ++--
 net/bluetooth/mgmt.c                          |  5 ++--
 net/core/pktgen.c                             | 25 ++++++++-----------
 net/ipv4/tcp_input.c                          |  2 +-
 net/ipv6/addrconf.c                           |  6 ++---
 net/netfilter/nf_nat_helper.c                 |  2 +-
 net/xfrm/xfrm_state.c                         |  2 +-
 25 files changed, 56 insertions(+), 64 deletions(-)

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index c09ae279ef32..9f74b7d71a50 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -53,7 +53,7 @@ static unsigned long int get_module_load_offset(void)
 		 */
 		if (module_load_offset == 0)
 			module_load_offset =
-				(get_random_u32_below(1024) + 1) * PAGE_SIZE;
+				get_random_u32_between(1, 1024 + 1) * PAGE_SIZE;
 		mutex_unlock(&module_kaslr_mutex);
 	}
 	return module_load_offset;
diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index 0f722f8f779b..f31c94855a09 100644
--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -253,7 +253,7 @@ static int pkcs1pad_encrypt(struct akcipher_request *req)
 	ps_end = ctx->key_size - req->src_len - 2;
 	req_ctx->in_buf[0] = 0x02;
 	for (i = 1; i < ps_end; i++)
-		req_ctx->in_buf[i] = 1 + get_random_u32_below(255);
+		req_ctx->in_buf[i] = get_random_u32_between(1, 256);
 	req_ctx->in_buf[ps_end] = 0x00;
 
 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 079923d43ce2..b09b9408ec44 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -962,11 +962,11 @@ static char *generate_random_sgl_divisions(struct test_sg_division *divs,
 		if (div == &divs[max_divs - 1] || get_random_u32_below(2) == 0)
 			this_len = remaining;
 		else
-			this_len = 1 + get_random_u32_below(remaining);
+			this_len = get_random_u32_between(1, remaining + 1);
 		div->proportion_of_total = this_len;
 
 		if (get_random_u32_below(4) == 0)
-			div->offset = (PAGE_SIZE - 128) + get_random_u32_below(128);
+			div->offset = get_random_u32_between(PAGE_SIZE - 128, PAGE_SIZE);
 		else if (get_random_u32_below(2) == 0)
 			div->offset = get_random_u32_below(32);
 		else
@@ -1094,12 +1094,12 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
 	}
 
 	if (get_random_u32_below(2) == 0) {
-		cfg->iv_offset = 1 + get_random_u32_below(MAX_ALGAPI_ALIGNMASK);
+		cfg->iv_offset = get_random_u32_between(1, MAX_ALGAPI_ALIGNMASK + 1);
 		p += scnprintf(p, end - p, " iv_offset=%u", cfg->iv_offset);
 	}
 
 	if (get_random_u32_below(2) == 0) {
-		cfg->key_offset = 1 + get_random_u32_below(MAX_ALGAPI_ALIGNMASK);
+		cfg->key_offset = get_random_u32_between(1, MAX_ALGAPI_ALIGNMASK + 1);
 		p += scnprintf(p, end - p, " key_offset=%u", cfg->key_offset);
 	}
 
@@ -1653,7 +1653,7 @@ static void generate_random_hash_testvec(struct shash_desc *desc,
 	if (maxkeysize) {
 		vec->ksize = maxkeysize;
 		if (get_random_u32_below(4) == 0)
-			vec->ksize = 1 + get_random_u32_below(maxkeysize);
+			vec->ksize = get_random_u32_between(1, maxkeysize + 1);
 		generate_random_bytes((u8 *)vec->key, vec->ksize);
 
 		vec->setkey_error = crypto_shash_setkey(desc->tfm, vec->key,
diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
index c73621aabbd1..cfb85d00ab6e 100644
--- a/drivers/bus/mhi/host/internal.h
+++ b/drivers/bus/mhi/host/internal.h
@@ -129,7 +129,7 @@ enum mhi_pm_state {
 #define PRIMARY_CMD_RING				0
 #define MHI_DEV_WAKE_DB					127
 #define MHI_MAX_MTU					0xffff
-#define MHI_RANDOM_U32_NONZERO(bmsk)			(get_random_u32_below(bmsk) + 1)
+#define MHI_RANDOM_U32_NONZERO(bmsk)			(get_random_u32_between(1, bmsk + 1))
 
 enum mhi_er_type {
 	MHI_ER_TYPE_INVALID = 0x0,
diff --git a/drivers/dma-buf/st-dma-fence-chain.c b/drivers/dma-buf/st-dma-fence-chain.c
index 9fbad7317d9b..bb46b57cc230 100644
--- a/drivers/dma-buf/st-dma-fence-chain.c
+++ b/drivers/dma-buf/st-dma-fence-chain.c
@@ -400,7 +400,7 @@ static int __find_race(void *arg)
 		struct dma_fence *fence = dma_fence_get(data->fc.tail);
 		int seqno;
 
-		seqno = get_random_u32_below(data->fc.chain_length) + 1;
+		seqno = get_random_u32_between(1, data->fc.chain_length + 1);
 
 		err = dma_fence_chain_find_seqno(&fence, seqno);
 		if (err) {
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 631e31718bd0..b8af158c9e37 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3807,7 +3807,7 @@ static int cma_alloc_any_port(enum rdma_ucm_port_space ps,
 
 	inet_get_local_port_range(net, &low, &high);
 	remaining = (high - low) + 1;
-	rover = get_random_u32_below(remaining) + low;
+	rover = get_random_u32_between(low, remaining + low);
 retry:
 	if (last_used_port != rover) {
 		struct rdma_bind_list *bind_list;
diff --git a/drivers/infiniband/hw/hns/hns_roce_ah.c b/drivers/infiniband/hw/hns/hns_roce_ah.c
index b37d2a81584d..02481487b203 100644
--- a/drivers/infiniband/hw/hns/hns_roce_ah.c
+++ b/drivers/infiniband/hw/hns/hns_roce_ah.c
@@ -41,9 +41,8 @@ static inline u16 get_ah_udp_sport(const struct rdma_ah_attr *ah_attr)
 	u16 sport;
 
 	if (!fl)
-		sport = get_random_u32_below(IB_ROCE_UDP_ENCAP_VALID_PORT_MAX +
-					     1 - IB_ROCE_UDP_ENCAP_VALID_PORT_MIN) +
-			IB_ROCE_UDP_ENCAP_VALID_PORT_MIN;
+		sport = get_random_u32_between(IB_ROCE_UDP_ENCAP_VALID_PORT_MIN,
+					       IB_ROCE_UDP_ENCAP_VALID_PORT_MAX + 1);
 	else
 		sport = rdma_flow_label_to_udp_sport(fl);
 
diff --git a/drivers/mtd/nand/raw/nandsim.c b/drivers/mtd/nand/raw/nandsim.c
index 274a31b93100..d4d7c6dac001 100644
--- a/drivers/mtd/nand/raw/nandsim.c
+++ b/drivers/mtd/nand/raw/nandsim.c
@@ -1405,7 +1405,7 @@ static void ns_do_bit_flips(struct nandsim *ns, int num)
 	if (bitflips && get_random_u16() < (1 << 6)) {
 		int flips = 1;
 		if (bitflips > 1)
-			flips = get_random_u32_below(bitflips) + 1;
+			flips = get_random_u32_between(1, bitflips + 1);
 		while (flips--) {
 			int pos = get_random_u32_below(num * 8);
 			ns->buf.byte[pos / 8] ^= (1 << (pos % 8));
diff --git a/drivers/net/wireguard/selftest/allowedips.c b/drivers/net/wireguard/selftest/allowedips.c
index 78a916f30c82..34d5981f4513 100644
--- a/drivers/net/wireguard/selftest/allowedips.c
+++ b/drivers/net/wireguard/selftest/allowedips.c
@@ -285,7 +285,7 @@ static __init bool randomized_test(void)
 
 	for (i = 0; i < NUM_RAND_ROUTES; ++i) {
 		get_random_bytes(ip, 4);
-		cidr = get_random_u32_below(32) + 1;
+		cidr = get_random_u32_between(1, 32 + 1);
 		peer = peers[get_random_u32_below(NUM_PEERS)];
 		if (wg_allowedips_insert_v4(&t, (struct in_addr *)ip, cidr,
 					    peer, &mutex) < 0) {
@@ -311,7 +311,7 @@ static __init bool randomized_test(void)
 				mutated[k] = (mutated[k] & mutate_mask[k]) |
 					     (~mutate_mask[k] &
 					      get_random_u8());
-			cidr = get_random_u32_below(32) + 1;
+			cidr = get_random_u32_between(1, 32 + 1);
 			peer = peers[get_random_u32_below(NUM_PEERS)];
 			if (wg_allowedips_insert_v4(&t,
 						    (struct in_addr *)mutated,
@@ -329,7 +329,7 @@ static __init bool randomized_test(void)
 
 	for (i = 0; i < NUM_RAND_ROUTES; ++i) {
 		get_random_bytes(ip, 16);
-		cidr = get_random_u32_below(128) + 1;
+		cidr = get_random_u32_between(1, 128 + 1);
 		peer = peers[get_random_u32_below(NUM_PEERS)];
 		if (wg_allowedips_insert_v6(&t, (struct in6_addr *)ip, cidr,
 					    peer, &mutex) < 0) {
@@ -355,7 +355,7 @@ static __init bool randomized_test(void)
 				mutated[k] = (mutated[k] & mutate_mask[k]) |
 					     (~mutate_mask[k] &
 					      get_random_u8());
-			cidr = get_random_u32_below(128) + 1;
+			cidr = get_random_u32_between(1, 128 + 1);
 			peer = peers[get_random_u32_below(NUM_PEERS)];
 			if (wg_allowedips_insert_v6(&t,
 						    (struct in6_addr *)mutated,
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
index 23c971b77965..0e6bf5e5c8a9 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
@@ -1128,7 +1128,7 @@ static void brcmf_p2p_afx_handler(struct work_struct *work)
 	if (afx_hdl->is_listen && afx_hdl->my_listen_chan)
 		/* 100ms ~ 300ms */
 		err = brcmf_p2p_discover_listen(p2p, afx_hdl->my_listen_chan,
-						100 * (1 + get_random_u32_below(3)));
+						100 * get_random_u32_between(1, 4));
 	else
 		err = brcmf_p2p_act_frm_search(p2p, afx_hdl->peer_listen_chan);
 
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
index 1696fbf1009a..f0b94633834e 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
@@ -1099,7 +1099,7 @@ static void iwl_mvm_mac_ctxt_cmd_fill_ap(struct iwl_mvm *mvm,
 			iwl_mvm_mac_ap_iterator, &data);
 
 		if (data.beacon_device_ts) {
-			u32 rand = get_random_u32_below(64 - 36) + 36;
+			u32 rand = get_random_u32_between(36, 64);
 			mvmvif->ap_beacon_time = data.beacon_device_ts +
 				ieee80211_tu_to_usec(data.beacon_int * rand /
 						     100);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 334415d946f8..8319fdc59fb4 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2588,7 +2588,7 @@ static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
 	curseg->alloc_type = LFS;
 	if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK)
 		curseg->fragment_remained_chunk =
-				get_random_u32_below(sbi->max_fragment_chunk) + 1;
+				get_random_u32_between(1, sbi->max_fragment_chunk + 1);
 }
 
 static int __next_free_blkoff(struct f2fs_sb_info *sbi,
@@ -2625,9 +2625,9 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
 			/* To allocate block chunks in different sizes, use random number */
 			if (--seg->fragment_remained_chunk <= 0) {
 				seg->fragment_remained_chunk =
-				   get_random_u32_below(sbi->max_fragment_chunk) + 1;
+				   get_random_u32_between(1, sbi->max_fragment_chunk + 1);
 				seg->next_blkoff +=
-				   get_random_u32_below(sbi->max_fragment_hole) + 1;
+				   get_random_u32_between(1, sbi->max_fragment_hole + 1);
 			}
 		}
 	}
diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c
index 7b619f16a492..eed30ad29796 100644
--- a/kernel/kcsan/selftest.c
+++ b/kernel/kcsan/selftest.c
@@ -31,7 +31,7 @@ static bool __init test_encode_decode(void)
 	int i;
 
 	for (i = 0; i < ITERS_PER_TEST; ++i) {
-		size_t size = get_random_u32_below(MAX_ENCODABLE_SIZE) + 1;
+		size_t size = get_random_u32_between(1, MAX_ENCODABLE_SIZE + 1);
 		bool is_write = !!get_random_u32_below(2);
 		unsigned long verif_masked_addr;
 		long encoded_watchpoint;
diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
index efc50fd30a44..f4ff3041ec10 100644
--- a/lib/test_hexdump.c
+++ b/lib/test_hexdump.c
@@ -149,7 +149,7 @@ static void __init test_hexdump(size_t len, int rowsize, int groupsize,
 static void __init test_hexdump_set(int rowsize, bool ascii)
 {
 	size_t d = min_t(size_t, sizeof(data_b), rowsize);
-	size_t len = get_random_u32_below(d) + 1;
+	size_t len = get_random_u32_between(1, d + 1);
 
 	test_hexdump(len, rowsize, 4, ascii);
 	test_hexdump(len, rowsize, 2, ascii);
@@ -208,11 +208,11 @@ static void __init test_hexdump_overflow(size_t buflen, size_t len,
 static void __init test_hexdump_overflow_set(size_t buflen, bool ascii)
 {
 	unsigned int i = 0;
-	int rs = (get_random_u32_below(2) + 1) * 16;
+	int rs = get_random_u32_between(1, 3) * 16;
 
 	do {
 		int gs = 1 << i;
-		size_t len = get_random_u32_below(rs) + gs;
+		size_t len = get_random_u32_between(gs, rs + gs);
 
 		test_hexdump_overflow(buflen, rounddown(len, gs), rs, gs, ascii);
 	} while (i++ < 3);
@@ -223,11 +223,11 @@ static int __init test_hexdump_init(void)
 	unsigned int i;
 	int rowsize;
 
-	rowsize = (get_random_u32_below(2) + 1) * 16;
+	rowsize = get_random_u32_between(1, 3) * 16;
 	for (i = 0; i < 16; i++)
 		test_hexdump_set(rowsize, false);
 
-	rowsize = (get_random_u32_below(2) + 1) * 16;
+	rowsize = get_random_u32_between(1, 3) * 16;
 	for (i = 0; i < 16; i++)
 		test_hexdump_set(rowsize, true);
 
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 6d10187eddac..da5efc8b8543 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -126,7 +126,7 @@ __test(const char *expect, int elen, const char *fmt, ...)
 	 * be able to print it as expected.
 	 */
 	failed_tests += do_test(BUF_SIZE, expect, elen, fmt, ap);
-	rand = 1 + get_random_u32_below(elen + 1);
+	rand = get_random_u32_between(1, elen + 2);
 	/* Since elen < BUF_SIZE, we have 1 <= rand <= BUF_SIZE. */
 	failed_tests += do_test(rand, expect, elen, fmt, ap);
 	failed_tests += do_test(0, expect, elen, fmt, ap);
diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 104f09ea5fcc..7a2caf4596c5 100644
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -151,7 +151,7 @@ static int random_size_alloc_test(void)
 	int i;
 
 	for (i = 0; i < test_loop_count; i++) {
-		n = get_random_u32_below(100) + 1;
+		n = get_random_u32_between(1, 101);
 		p = vmalloc(n * PAGE_SIZE);
 
 		if (!p)
@@ -291,12 +291,12 @@ pcpu_alloc_test(void)
 		return -1;
 
 	for (i = 0; i < 35000; i++) {
-		size = get_random_u32_below(PAGE_SIZE / 4) + 1;
+		size = get_random_u32_between(1, PAGE_SIZE / 4 + 1);
 
 		/*
 		 * Maximum PAGE_SIZE
 		 */
-		align = 1 << (get_random_u32_below(11) + 1);
+		align = 1 << get_random_u32_between(1, 12);
 
 		pcpu[i] = __alloc_percpu(size, align);
 		if (!pcpu[i])
diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 640f9c7f8e44..6167e19056f0 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -1299,7 +1299,7 @@ static void match_all_not_assigned(struct kunit *test)
 	KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
 
 	for (i = 0; i < 256; i++) {
-		size = get_random_u32_below(1024) + 1;
+		size = get_random_u32_between(1, 1024 + 1);
 		ptr = kmalloc(size, GFP_KERNEL);
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 		KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
@@ -1308,7 +1308,7 @@ static void match_all_not_assigned(struct kunit *test)
 	}
 
 	for (i = 0; i < 256; i++) {
-		order = get_random_u32_below(4) + 1;
+		order = get_random_u32_between(1, 5);
 		pages = alloc_pages(GFP_KERNEL, order);
 		ptr = page_address(pages);
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
@@ -1321,7 +1321,7 @@ static void match_all_not_assigned(struct kunit *test)
 		return;
 
 	for (i = 0; i < 256; i++) {
-		size = get_random_u32_below(1024) + 1;
+		size = get_random_u32_between(1, 1024 + 1);
 		ptr = vmalloc(size);
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 		KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c
index 20028c179796..99abe86fc9b1 100644
--- a/mm/kfence/kfence_test.c
+++ b/mm/kfence/kfence_test.c
@@ -532,7 +532,7 @@ static void test_free_bulk(struct kunit *test)
 	int iter;
 
 	for (iter = 0; iter < 5; iter++) {
-		const size_t size = setup_test_cache(test, 8 + get_random_u32_below(300),
+		const size_t size = setup_test_cache(test, get_random_u32_between(8, 308),
 						     0, (iter & 1) ? ctor_set_x : NULL);
 		void *objects[] = {
 			test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT),
diff --git a/mm/swapfile.c b/mm/swapfile.c
index e9318305a24a..08f0152c32da 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -772,8 +772,7 @@ static void set_cluster_next(struct swap_info_struct *si, unsigned long next)
 		/* No free swap slots available */
 		if (si->highest_bit <= si->lowest_bit)
 			return;
-		next = si->lowest_bit +
-			get_random_u32_below(si->highest_bit - si->lowest_bit + 1);
+		next = get_random_u32_between(si->lowest_bit, si->highest_bit + 1);
 		next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES);
 		next = max_t(unsigned int, next, si->lowest_bit);
 	}
@@ -3089,7 +3088,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		 */
 		for_each_possible_cpu(cpu) {
 			per_cpu(*p->cluster_next_cpu, cpu) =
-				1 + get_random_u32_below(p->highest_bit);
+				get_random_u32_between(1, p->highest_bit + 1);
 		}
 		nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
 
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index b2f9679066c4..bab37a529db5 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7373,9 +7373,8 @@ static int get_conn_info(struct sock *sk, struct hci_dev *hdev, void *data,
 	/* To avoid client trying to guess when to poll again for information we
 	 * calculate conn info age as random value between min/max set in hdev.
 	 */
-	conn_info_age = hdev->conn_info_min_age +
-			get_random_u32_below(hdev->conn_info_max_age -
-					     hdev->conn_info_min_age);
+	conn_info_age = get_random_u32_between(hdev->conn_info_min_age,
+					       hdev->conn_info_max_age);
 
 	/* Query controller to refresh cached values if they are too old or were
 	 * never read.
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 95da2ddc1c20..5eb401003368 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2380,9 +2380,8 @@ static void set_cur_queue_map(struct pktgen_dev *pkt_dev)
 	else if (pkt_dev->queue_map_min <= pkt_dev->queue_map_max) {
 		__u16 t;
 		if (pkt_dev->flags & F_QUEUE_MAP_RND) {
-			t = get_random_u32_below(pkt_dev->queue_map_max -
-						 pkt_dev->queue_map_min + 1) +
-			    pkt_dev->queue_map_min;
+			t = get_random_u32_between(pkt_dev->queue_map_min,
+						   pkt_dev->queue_map_max + 1);
 		} else {
 			t = pkt_dev->cur_queue_map + 1;
 			if (t > pkt_dev->queue_map_max)
@@ -2478,9 +2477,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 
 	if (pkt_dev->udp_src_min < pkt_dev->udp_src_max) {
 		if (pkt_dev->flags & F_UDPSRC_RND)
-			pkt_dev->cur_udp_src = get_random_u32_below(
-				pkt_dev->udp_src_max - pkt_dev->udp_src_min) +
-				pkt_dev->udp_src_min;
+			pkt_dev->cur_udp_src = get_random_u32_between(pkt_dev->udp_src_min,
+								      pkt_dev->udp_src_max);
 
 		else {
 			pkt_dev->cur_udp_src++;
@@ -2491,9 +2489,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 
 	if (pkt_dev->udp_dst_min < pkt_dev->udp_dst_max) {
 		if (pkt_dev->flags & F_UDPDST_RND) {
-			pkt_dev->cur_udp_dst = get_random_u32_below(
-				pkt_dev->udp_dst_max - pkt_dev->udp_dst_min) +
-				pkt_dev->udp_dst_min;
+			pkt_dev->cur_udp_dst = get_random_u32_between(pkt_dev->udp_dst_min,
+								      pkt_dev->udp_dst_max);
 		} else {
 			pkt_dev->cur_udp_dst++;
 			if (pkt_dev->cur_udp_dst >= pkt_dev->udp_dst_max)
@@ -2508,7 +2505,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 		if (imn < imx) {
 			__u32 t;
 			if (pkt_dev->flags & F_IPSRC_RND)
-				t = get_random_u32_below(imx - imn) + imn;
+				t = get_random_u32_between(imn, imx);
 			else {
 				t = ntohl(pkt_dev->cur_saddr);
 				t++;
@@ -2530,8 +2527,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 				if (pkt_dev->flags & F_IPDST_RND) {
 
 					do {
-						t = get_random_u32_below(imx - imn) +
-						    imn;
+						t = get_random_u32_between(imn, imx);
 						s = htonl(t);
 					} while (ipv4_is_loopback(s) ||
 						ipv4_is_multicast(s) ||
@@ -2578,9 +2574,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 	if (pkt_dev->min_pkt_size < pkt_dev->max_pkt_size) {
 		__u32 t;
 		if (pkt_dev->flags & F_TXSIZE_RND) {
-			t = get_random_u32_below(pkt_dev->max_pkt_size -
-						 pkt_dev->min_pkt_size) +
-			    pkt_dev->min_pkt_size;
+			t = get_random_u32_between(pkt_dev->min_pkt_size,
+						   pkt_dev->max_pkt_size);
 		} else {
 			t = pkt_dev->cur_pkt_size + 1;
 			if (t > pkt_dev->max_pkt_size)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f90cadd9ba5c..27fcc33d16f5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3646,7 +3646,7 @@ static void tcp_send_challenge_ack(struct sock *sk)
 
 		WRITE_ONCE(net->ipv4.tcp_challenge_timestamp, now);
 		WRITE_ONCE(net->ipv4.tcp_challenge_count,
-			   half + get_random_u32_below(ack_limit));
+			   get_random_u32_between(half, ack_limit + half));
 	}
 	count = READ_ONCE(net->ipv4.tcp_challenge_count);
 	if (count > 0) {
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d5551d9e382d..3238a9246548 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -104,7 +104,7 @@ static inline u32 cstamp_delta(unsigned long cstamp)
 static inline s32 rfc3315_s14_backoff_init(s32 irt)
 {
 	/* multiply 'initial retransmission time' by 0.9 .. 1.1 */
-	u64 tmp = (900000 + get_random_u32_below(200001)) * (u64)irt;
+	u64 tmp = get_random_u32_between(900000, 1100001) * (u64)irt;
 	do_div(tmp, 1000000);
 	return (s32)tmp;
 }
@@ -112,11 +112,11 @@ static inline s32 rfc3315_s14_backoff_init(s32 irt)
 static inline s32 rfc3315_s14_backoff_update(s32 rt, s32 mrt)
 {
 	/* multiply 'retransmission timeout' by 1.9 .. 2.1 */
-	u64 tmp = (1900000 + get_random_u32_below(200001)) * (u64)rt;
+	u64 tmp = get_random_u32_between(1900000, 2100001) * (u64)rt;
 	do_div(tmp, 1000000);
 	if ((s32)tmp > mrt) {
 		/* multiply 'maximum retransmission time' by 0.9 .. 1.1 */
-		tmp = (900000 + get_random_u32_below(200001)) * (u64)mrt;
+		tmp = get_random_u32_between(900000, 1100001) * (u64)mrt;
 		do_div(tmp, 1000000);
 	}
 	return (s32)tmp;
diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index bf591e6af005..a12c3470f7fd 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -223,7 +223,7 @@ u16 nf_nat_exp_find_port(struct nf_conntrack_expect *exp, u16 port)
 		if (res != -EBUSY || (--attempts_left < 0))
 			break;
 
-		port = min + get_random_u32_below(range);
+		port = get_random_u32_between(min, range + min);
 	}
 
 	return 0;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 40f831854774..c118476f73ae 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2072,7 +2072,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high)
 	} else {
 		u32 spi = 0;
 		for (h = 0; h < high-low+1; h++) {
-			spi = low + get_random_u32_below(high - low + 1);
+			spi = get_random_u32_between(low, high + 1);
 			x0 = xfrm_state_lookup(net, mark, &x->id.daddr, htonl(spi), x->id.proto, x->props.family);
 			if (x0 == NULL) {
 				newspi = htonl(spi);
-- 
2.38.1


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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jakub Kicinski]

On Fri, 21 Oct 2022 21:43:58 -0400 Jason A. Donenfeld wrote:
> Since get_random_u32_below() sits in my random.git tree, these patches
> too will flow through that same tree.

How big is it?  Can you provide a stable branch to pull in the new
helpers and then everyone will be able to apply the patches to their
subsystem?


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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jason A. Donenfeld]

On Fri, Oct 21, 2022 at 08:55:22PM -0700, Jakub Kicinski wrote:
> On Fri, 21 Oct 2022 21:43:58 -0400 Jason A. Donenfeld wrote:
> > Since get_random_u32_below() sits in my random.git tree, these patches
> > too will flow through that same tree.
> 
> How big is it?  Can you provide a stable branch to pull in the new
> helpers and then everyone will be able to apply the patches to their
> subsystem?

It's a patch. But what you suggest sounds crazy to me. Supply some
branch and have every tree merge that branch separately, in duplicate,
and then get all of the conversion patches through every tree, and then
somehow coordinate the removal of the deprecated function after all of
that, and then baby sit the grand orchestration of all this over the
course of two and half months, watch it fail because of some
unmaintained corner that's affected, and then try to herd it through for
another two and a half months after that? Holy crap. That's torture.

Were this an actually technically interesting patchset that required
some really detailed expert review, maybe that'd have some iota of
merit. But this is a really boring refactoring, mostly automated with
Coccinelle. If having to baby sit one hundred separate patches over the
course of months, handling confusion of walking maintainers through the
exercise of merging some weird duplicate branch into their trees before,
and so forth, is required to get this kind of grunt work done, I'm just
going to wind up losing all motivation for this kind of thing, and
naturally, as a matter of human nature, stop doing it. The result will
be that we have garbage pile up over time that operates on the principle
of "least hassle to deal with for the time being" rather than "love of
the code and a desire for long term maintainability and quality". The
former is sometimes how things go. The latter is what I'm striving for.

So what you suggest sounds really dreadful to me. Sorry.

Instead, this series follows the same template as the last one, and the
last one was much more nuanced and invasive and went fine. In the very
worst case, it'll require me to be on the ball with what's happening
with -next, which is something I've done before and can do again.

Jason

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jakub Kicinski]

On Sat, 22 Oct 2022 00:23:00 -0400 Jason A. Donenfeld wrote:
> > How big is it?  Can you provide a stable branch to pull in the new
> > helpers and then everyone will be able to apply the patches to their
> > subsystem?  
> 
> It's a patch. But what you suggest sounds crazy to me. Supply some
> branch and have every tree merge that branch separately, in duplicate,
> and then get all of the conversion patches through every tree, and then
> somehow coordinate the removal of the deprecated function after all of
> that, and then baby sit the grand orchestration of all this over the
> course of two and half months, watch it fail because of some
> unmaintained corner that's affected, and then try to herd it through for
> another two and a half months after that? Holy crap. That's torture.

I clean up some random networking API every couple of releases.
Unfortunately other subsystems use networking APIs too, so I have 
to do what you describe as "torture". It's not that hard in my
experience but perhaps I'm incredibly gifted. Or resilient to pain.

> Were this an actually technically interesting patchset that required
> some really detailed expert review, maybe that'd have some iota of
> merit. But this is a really boring refactoring, mostly automated with
> Coccinelle. If having to baby sit one hundred separate patches over the
> course of months, handling confusion of walking maintainers through the
> exercise of merging some weird duplicate branch into their trees before,
> and so forth, is required to get this kind of grunt work done, I'm just
> going to wind up losing all motivation for this kind of thing, and
> naturally, as a matter of human nature, stop doing it. The result will
> be that we have garbage pile up over time that operates on the principle
> of "least hassle to deal with for the time being" rather than "love of
> the code and a desire for long term maintainability and quality". The
> former is sometimes how things go. The latter is what I'm striving for.
> 
> So what you suggest sounds really dreadful to me. Sorry.
> 
> Instead, this series follows the same template as the last one, and the
> last one was much more nuanced and invasive and went fine. In the very
> worst case, it'll require me to be on the ball with what's happening
> with -next, which is something I've done before and can do again.

Not sure what you mean by "being on the ball with what's happening with
-next" surely it's Steven who'll be fixing the conflicts and paying
with his time? Or carrying extra patches because neither you will be
able to convert the new cases in your tree nor in the origin tree since
it won't have your new helpers.

To me putting the new helpers first, on a clean branch off Linus's tree
so in case of emergency it can be pulled into a random^W arbitrary tree
is just good hygiene.

But whatever. I mean - hopefully there aren't any conflicts in the ~50
networking files you touch. I just wish that people didn't pipe up with
the tree wide changes right after the merge window. Feels like the
worst possible timing.

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jason A. Donenfeld]

On Fri, Oct 21, 2022 at 10:32:42PM -0700, Jakub Kicinski wrote:
> But whatever. I mean - hopefully there aren't any conflicts in the ~50
> networking files you touch. I just wish that people didn't pipe up with
> the tree wide changes right after the merge window. Feels like the
> worst possible timing.

Oh, if the timing is what makes this especially worrisome, I have
no qualms about rebasing much later, and reposting this series then.
I'll do that.

Jason

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jakub Kicinski]

On Sat, 22 Oct 2022 07:47:06 +0200 Jason A. Donenfeld wrote:
> On Fri, Oct 21, 2022 at 10:32:42PM -0700, Jakub Kicinski wrote:
> > But whatever. I mean - hopefully there aren't any conflicts in the ~50
> > networking files you touch. I just wish that people didn't pipe up with
> > the tree wide changes right after the merge window. Feels like the
> > worst possible timing.  
> 
> Oh, if the timing is what makes this especially worrisome, I have
> no qualms about rebasing much later, and reposting this series then.
> I'll do that.

Cool, thanks! I promise to not be grumpy if you repost around rc6 :)

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Theodore Ts'o]

On Fri, Oct 21, 2022 at 11:03:22PM -0700, Jakub Kicinski wrote:
> On Sat, 22 Oct 2022 07:47:06 +0200 Jason A. Donenfeld wrote:
> > On Fri, Oct 21, 2022 at 10:32:42PM -0700, Jakub Kicinski wrote:
> > > But whatever. I mean - hopefully there aren't any conflicts in the ~50
> > > networking files you touch. I just wish that people didn't pipe up with
> > > the tree wide changes right after the merge window. Feels like the
> > > worst possible timing.  
> > 
> > Oh, if the timing is what makes this especially worrisome, I have
> > no qualms about rebasing much later, and reposting this series then.
> > I'll do that.
> 
> Cool, thanks! I promise to not be grumpy if you repost around rc6 :)

One way of making things less painful for the stable branch and for
the upstream branch is to *add* new helpers instead of playing
replacement games like s/prandom_u32_max/get_random_u32_below/.  This
is what causes the patch conflict problems.

One advantage of at least adding the new functions to the stable
branches, even if we don't do the wholesale replacement, is that it
makes it much less likely that a backported patch, which uses the new
API, won't fail to compile --- and of course, the major headache case
is one where it's not noticed at first because it didn't get picked up
in people's test compiles until after the Linux x.y.z release has been
pushed out.

Whether it's worth doing the wholesale replacement is a different
question, but separating "add the new functions with one or two use
cases so the functions are actulaly _used_" from the "convert the
world to use the new functions" from the "remove the old functions",
might life easier.

					- Ted

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jason A. Donenfeld]

On Sun, Oct 23, 2022 at 05:07:13PM -0400, Theodore Ts'o wrote:
> On Fri, Oct 21, 2022 at 11:03:22PM -0700, Jakub Kicinski wrote:
> > On Sat, 22 Oct 2022 07:47:06 +0200 Jason A. Donenfeld wrote:
> > > On Fri, Oct 21, 2022 at 10:32:42PM -0700, Jakub Kicinski wrote:
> > > > But whatever. I mean - hopefully there aren't any conflicts in the ~50
> > > > networking files you touch. I just wish that people didn't pipe up with
> > > > the tree wide changes right after the merge window. Feels like the
> > > > worst possible timing.  
> > > 
> > > Oh, if the timing is what makes this especially worrisome, I have
> > > no qualms about rebasing much later, and reposting this series then.
> > > I'll do that.
> > 
> > Cool, thanks! I promise to not be grumpy if you repost around rc6 :)
> 
> One way of making things less painful for the stable branch and for
> the upstream branch is to *add* new helpers instead of playing
> replacement games like s/prandom_u32_max/get_random_u32_below/.  This
> is what causes the patch conflict problems.
> 
> One advantage of at least adding the new functions to the stable
> branches, even if we don't do the wholesale replacement, is that it

That's a good idea. I'll also save the removal commit, anyhow, for a
separate thing at the end of 6.2 rc1, so that -next doesn't have issues
either.  That's how things wound up going down for the first tranche of
these, and that worked well.

Jason

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Greg Kroah-Hartman]

On Fri, Oct 21, 2022 at 09:43:58PM -0400, Jason A. Donenfeld wrote:
> Hey everyone,
> 
> Here's the second and final tranche of tree-wide conversions to get
> random integer handling a bit tamer. It's predominantly another
> Coccinelle-based patchset.
> 
> First we s/prandom_u32_max/get_random_u32_below/, since the former is
> just a deprecated alias for the latter. Then in the next commit we can
> remove prandom_u32_max all together. I'm quite happy about finally being
> able to do that. It means that prandom.h is now only for deterministic and 
> repeatable randomness, not non-deterministic/cryptographic randomness.
> That line is no longer blurred.
> 
> Then, in order to clean up a bunch of inefficient patterns, we introduce
> two trivial static inline helper functions built on top of
> get_random_u32_below: get_random_u32_above and get_random_u32_between.
> These are pretty straight forward to use and understand. Then the final
> two patches convert some gnarly open-coded number juggling to use these
> helpers.
> 
> I've used Coccinelle for all the treewide patches, so hopefully review
> is rather uneventful. I didn't accept all of the changes that Coccinelle
> proposed, though, as these tend to be somewhat context-specific. I erred
> on the side of just going with the most obvious cases, at least this
> time through. And then we can address more complicated cases through
> actual maintainer trees.
> 
> Since get_random_u32_below() sits in my random.git tree, these patches
> too will flow through that same tree.
> 
> Regards,
> Jason


Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Re: [PATCH v1 0/5] convert tree to get_random_u32_{below,above,between}()

[Jason Gunthorpe]

On Fri, Oct 21, 2022 at 09:43:58PM -0400, Jason A. Donenfeld wrote:
> Hey everyone,
> 
> Here's the second and final tranche of tree-wide conversions to get
> random integer handling a bit tamer. It's predominantly another
> Coccinelle-based patchset.
> 
> First we s/prandom_u32_max/get_random_u32_below/, since the former is
> just a deprecated alias for the latter. Then in the next commit we can
> remove prandom_u32_max all together. I'm quite happy about finally being
> able to do that. It means that prandom.h is now only for deterministic and 
> repeatable randomness, not non-deterministic/cryptographic randomness.
> That line is no longer blurred.
> 
> Then, in order to clean up a bunch of inefficient patterns, we introduce
> two trivial static inline helper functions built on top of
> get_random_u32_below: get_random_u32_above and get_random_u32_between.
> These are pretty straight forward to use and understand. Then the final
> two patches convert some gnarly open-coded number juggling to use these
> helpers.
> 
> I've used Coccinelle for all the treewide patches, so hopefully review
> is rather uneventful. I didn't accept all of the changes that Coccinelle
> proposed, though, as these tend to be somewhat context-specific. I erred
> on the side of just going with the most obvious cases, at least this
> time through. And then we can address more complicated cases through
> actual maintainer trees.
> 
> Since get_random_u32_below() sits in my random.git tree, these patches
> too will flow through that same tree.
> 
For drivers/infiniband

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

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