From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from abb.hmeau.com (abb.hmeau.com [180.181.231.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C901424B28; Mon, 24 Nov 2025 09:54:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=180.181.231.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763978079; cv=none; b=OrhBTwl6BMqS8pYcfarqR9HGAhSeI26vREWeXj7sBtD3362M7aMbqTWKdvA+MacwqTfvv60xSfYJrLX5R7ZY13HB4AG4msj+1X0S9R+Z/MP740gcweSDj6N1kvAhRDqqwqzdmvUcPjbfzOSF6WcoccepgvIZ1DE8k4B1kYcckKQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763978079; c=relaxed/simple; bh=zgUegguLz9fnh3Kc5FyiFvVdDbDa4+bOp5Www3PDcuc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ctY5ec1pVMPgAQziivIuyNMUNBBzBLjHqXG57D/iuzXjRNcJdrcJjU9kdacC12pvOLum/X7GMW/2XgVUnWfvsJJolpF2qFqE3iXEuv3DrL1T+h/W/fWPLtntbF/kEBoAZhmjDER1oIdcu/C7H+zIkeFDv76zc8PF6r9/vuR0yyU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au; spf=pass smtp.mailfrom=gondor.apana.org.au; dkim=pass (2048-bit key) header.d=gondor.apana.org.au header.i=@gondor.apana.org.au header.b=P87gnIuA; arc=none smtp.client-ip=180.181.231.80 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gondor.apana.org.au header.i=@gondor.apana.org.au header.b="P87gnIuA" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gondor.apana.org.au; s=h01; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:cc:to:subject:message-id:date: from:content-type:reply-to; bh=B05uJapQfRMGohKkgF1xNVyERBHmagh8Bd3xg1q2NeI=; b=P87gnIuANW/TJp73uiT1mmsGlTWnBuH0H7vh23lNqSWq4OBDSGmsQEtkmAFMHotC7U4wL6z8BsM xZhrA2DnJ6Byz1eNq9hCgsl0YlQqjChTspvActJHQABJusXSSyN3NViM7BAWMow9uYLi6/azgr/1S bPNPkqeI4K++8lXngyxVPKygWdoefLDaHUV8R9vP4h+Voyby/LgDfyG/U2ZiZD9XFH7HpGmBTtoYh gxxkqEEHWY1my7y2fTHFr9TydDJrVMgiVb3KBgJmEGPf57jfBn092eZeVh0rkWj5FfVDm/r5gwJdx bl004005PGTqWH4a9OI+Nq6nG2BqQ4oMU7WA==; Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.96 #2 (Debian)) id 1vNTCh-005XNj-0w; Mon, 24 Nov 2025 17:49:52 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Mon, 24 Nov 2025 17:49:51 +0800 Date: Mon, 24 Nov 2025 17:49:51 +0800 From: Herbert Xu To: david.laight.linux@gmail.com Cc: linux-kernel@vger.kernel.org, Alan Stern , Alexander Viro , Alexei Starovoitov , Andi Shyti , Andreas Dilger , Andrew Lunn , Andrew Morton , Andrii Nakryiko , Andy Shevchenko , Ard Biesheuvel , Arnaldo Carvalho de Melo , Bjorn Helgaas , Borislav Petkov , Christian Brauner , Christian =?iso-8859-1?Q?K=F6nig?= , Christoph Hellwig , Daniel Borkmann , Dan Williams , Dave Hansen , Dave Jiang , David Ahern , David Hildenbrand , Davidlohr Bueso , "David S. Miller" , Dennis Zhou , Eric Dumazet , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jakub Sitnicki , "James E.J. Bottomley" , Jarkko Sakkinen , "Jason A. Donenfeld" , Jens Axboe , Jiri Slaby , Johannes Weiner , John Allen , Jonathan Cameron , Juergen Gross , Kees Cook , KP Singh , Linus Walleij , "Martin K. Petersen" , "Matthew Wilcox (Oracle)" , Mika Westerberg , Mike Rapoport , Miklos Szeredi , Namhyung Kim , Neal Cardwell , nic_swsd@realtek.com, OGAWA Hirofumi , Olivia Mackall , Paolo Abeni , Paolo Bonzini , Peter Huewe , Peter Zijlstra , "Rafael J. Wysocki" , Sean Christopherson , Srinivas Kandagatla , Stefano Stabellini , Steven Rostedt , Tejun Heo , Theodore Ts'o , Thomas Gleixner , Tom Lendacky , Willem de Bruijn , x86@kernel.org, Yury Norov , amd-gfx@lists.freedesktop.org, bpf@vger.kernel.org, cgroups@vger.kernel.org, dri-devel@lists.freedesktop.org, io-uring@vger.kernel.org, kvm@vger.kernel.org, linux-acpi@vger.kernel.org, linux-block@vger.kernel.org, linux-crypto@vger.kernel.org, linux-cxl@vger.kernel.org, linux-efi@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org, linux-integrity@vger.kernel.org, linux-mm@kvack.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-scsi@vger.kernel.org, linux-serial@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-usb@vger.kernel.org, mptcp@lists.linux.dev, netdev@vger.kernel.org, usb-storage@lists.one-eyed-alien.net Subject: Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits Message-ID: References: <20251119224140.8616-1-david.laight.linux@gmail.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251119224140.8616-1-david.laight.linux@gmail.com> On Wed, Nov 19, 2025 at 10:40:56PM +0000, david.laight.linux@gmail.com wrote: > From: David Laight > > It in not uncommon for code to use min_t(uint, a, b) when one of a or b > is 64bit and can have a value that is larger than 2^32; > This is particularly prevelant with: > uint_var = min_t(uint, uint_var, uint64_expression); > > Casts to u8 and u16 are very likely to discard significant bits. > > These can be detected at compile time by changing min_t(), for example: > #define CHECK_SIZE(fn, type, val) \ > BUILD_BUG_ON_MSG(sizeof (val) > sizeof (type) && \ > !statically_true(((val) >> 8 * (sizeof (type) - 1)) < 256), \ > fn "() significant bits of '" #val "' may be discarded") > > #define min_t(type, x, y) ({ \ > CHECK_SIZE("min_t", type, x); \ > CHECK_SIZE("min_t", type, y); \ > __cmp_once(min, type, x, y); }) > > (and similar changes to max_t() and clamp_t().) > > This shows up some real bugs, some unlikely bugs and some false positives. > In most cases both arguments are unsigned type (just different ones) > and min_t() can just be replaced by min(). > > The patches are all independant and are most of the ones needed to > get the x86-64 kernel I build to compile. > I've not tried building an allyesconfig or allmodconfig kernel. > I've also not included the patch to minmax.h itself. > > I've tried to put the patches that actually fix things first. > The last one is 0009. > > I gave up on fixing sched/fair.c - it is too broken for a single patch! > The patch for net/ipv4/tcp.c is also absent because do_tcp_getsockopt() > needs multiple/larger changes to make it 'sane'. > > I've had to trim the 124 maintainers/lists that get_maintainer.pl finds > from 124 to under 100 to be able to send the cover letter. > The individual patches only go to the addresses found for the associated files. > That reduces the number of emails to a less unsane number. > > David Laight (44): > x86/asm/bitops: Change the return type of variable__ffs() to unsigned > int > ext4: Fix saturation of 64bit inode times for old filesystems > perf: Fix branch stack callchain limit > io_uring/net: Change some dubious min_t() > ipc/msg: Fix saturation of percpu counts in msgctl_info() > bpf: Verifier, remove some unusual uses of min_t() and max_t() > net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value. > net: ethtool: Use min3() instead of nested min_t(u16,...) > ipv6: __ip6_append_data() don't abuse max_t() casts > x86/crypto: ctr_crypt() use min() instead of min_t() > arch/x96/kvm: use min() instead of min_t() > block: use min() instead of min_t() > drivers/acpi: use min() instead of min_t() > drivers/char/hw_random: use min3() instead of nested min_t() > drivers/char/tpm: use min() instead of min_t() > drivers/crypto/ccp: use min() instead of min_t() > drivers/cxl: use min() instead of min_t() > drivers/gpio: use min() instead of min_t() > drivers/gpu/drm/amd: use min() instead of min_t() > drivers/i2c/busses: use min() instead of min_t() > drivers/net/ethernet/realtek: use min() instead of min_t() > drivers/nvme: use min() instead of min_t() > arch/x86/mm: use min() instead of min_t() > drivers/nvmem: use min() instead of min_t() > drivers/pci: use min() instead of min_t() > drivers/scsi: use min() instead of min_t() > drivers/tty/vt: use umin() instead of min_t(u16, ...) for row/col > limits > drivers/usb/storage: use min() instead of min_t() > drivers/xen: use min() instead of min_t() > fs: use min() or umin() instead of min_t() > block: bvec.h: use min() instead of min_t() > nodemask: use min() instead of min_t() > ipc: use min() instead of min_t() > bpf: use min() instead of min_t() > bpf_trace: use min() instead of min_t() > lib/bucket_locks: use min() instead of min_t() > lib/crypto/mpi: use min() instead of min_t() > lib/dynamic_queue_limits: use max() instead of max_t() > mm: use min() instead of min_t() > net: Don't pass bitfields to max_t() > net/core: Change loop conditions so min() can be used > net: use min() instead of min_t() > net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits > net/mptcp: Change some dubious min_t(int, ...) to min() > > arch/x86/crypto/aesni-intel_glue.c | 3 +- > arch/x86/include/asm/bitops.h | 18 +++++------- > arch/x86/kvm/emulate.c | 3 +- > arch/x86/kvm/lapic.c | 2 +- > arch/x86/kvm/mmu/mmu.c | 2 +- > arch/x86/mm/pat/set_memory.c | 12 ++++---- > block/blk-iocost.c | 6 ++-- > block/blk-settings.c | 2 +- > block/partitions/efi.c | 3 +- > drivers/acpi/property.c | 2 +- > drivers/char/hw_random/core.c | 2 +- > drivers/char/tpm/tpm1-cmd.c | 2 +- > drivers/char/tpm/tpm_tis_core.c | 4 +-- > drivers/crypto/ccp/ccp-dev.c | 2 +- > drivers/cxl/core/mbox.c | 2 +- > drivers/gpio/gpiolib-acpi-core.c | 2 +- > .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c | 4 +-- > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +- > drivers/i2c/busses/i2c-designware-master.c | 2 +- > drivers/net/ethernet/realtek/r8169_main.c | 3 +- > drivers/nvme/host/pci.c | 3 +- > drivers/nvme/host/zns.c | 3 +- > drivers/nvmem/core.c | 2 +- > drivers/pci/probe.c | 3 +- > drivers/scsi/hosts.c | 2 +- > drivers/tty/vt/selection.c | 9 +++--- > drivers/usb/storage/protocol.c | 3 +- > drivers/xen/grant-table.c | 2 +- > fs/buffer.c | 2 +- > fs/exec.c | 2 +- > fs/ext4/ext4.h | 2 +- > fs/ext4/mballoc.c | 3 +- > fs/ext4/resize.c | 2 +- > fs/ext4/super.c | 2 +- > fs/fat/dir.c | 4 +-- > fs/fat/file.c | 3 +- > fs/fuse/dev.c | 2 +- > fs/fuse/file.c | 8 ++--- > fs/splice.c | 2 +- > include/linux/bvec.h | 3 +- > include/linux/nodemask.h | 9 +++--- > include/linux/perf_event.h | 2 +- > include/net/tcp_ecn.h | 5 ++-- > io_uring/net.c | 6 ++-- > ipc/mqueue.c | 4 +-- > ipc/msg.c | 6 ++-- > kernel/bpf/core.c | 4 +-- > kernel/bpf/log.c | 2 +- > kernel/bpf/verifier.c | 29 +++++++------------ > kernel/trace/bpf_trace.c | 2 +- > lib/bucket_locks.c | 2 +- > lib/crypto/mpi/mpicoder.c | 2 +- > lib/dynamic_queue_limits.c | 2 +- > mm/gup.c | 4 +-- > mm/memblock.c | 2 +- > mm/memory.c | 2 +- > mm/percpu.c | 2 +- > mm/truncate.c | 3 +- > mm/vmscan.c | 2 +- > net/core/datagram.c | 6 ++-- > net/core/flow_dissector.c | 7 ++--- > net/core/net-sysfs.c | 3 +- > net/core/skmsg.c | 4 +-- > net/ethtool/cmis_cdb.c | 7 ++--- > net/ipv4/fib_trie.c | 2 +- > net/ipv4/tcp_input.c | 4 +-- > net/ipv4/tcp_output.c | 5 ++-- > net/ipv4/tcp_timer.c | 4 +-- > net/ipv6/addrconf.c | 8 ++--- > net/ipv6/ip6_output.c | 7 +++-- > net/ipv6/ndisc.c | 5 ++-- > net/mptcp/protocol.c | 8 ++--- > net/netlink/genetlink.c | 9 +++--- > net/packet/af_packet.c | 2 +- > net/unix/af_unix.c | 4 +-- > 76 files changed, 141 insertions(+), 176 deletions(-) Patches 10,14,16,37 applied. Thanks. -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt