* [PATCH 18/44] drivers/gpio: use min() instead of min_t()
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
@ 2025-11-19 22:41 ` david.laight.linux
2025-11-20 8:01 ` Andy Shevchenko
2025-11-20 1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: david.laight.linux @ 2025-11-19 22:41 UTC (permalink / raw)
To: linux-kernel, linux-acpi, linux-gpio
Cc: Andy Shevchenko, Bartosz Golaszewski, Linus Walleij,
Mika Westerberg, David Laight
From: David Laight <david.laight.linux@gmail.com>
min_t(u16, a, b) casts an 'unsigned long' to 'u16'.
Use min(a, b) instead as it promotes the both values to int
and so cannot discard significant bits.
In this case the values should be ok.
Detected by an extra check added to min_t().
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
drivers/gpio/gpiolib-acpi-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
index d441c1236d8c..83dd227dbbec 100644
--- a/drivers/gpio/gpiolib-acpi-core.c
+++ b/drivers/gpio/gpiolib-acpi-core.c
@@ -1099,7 +1099,7 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
return AE_BAD_PARAMETER;
}
- length = min_t(u16, agpio->pin_table_length, pin_index + bits);
+ length = min(agpio->pin_table_length, pin_index + bits);
for (i = pin_index; i < length; ++i) {
unsigned int pin = agpio->pin_table[i];
struct acpi_gpio_connection *conn;
--
2.39.5
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH 18/44] drivers/gpio: use min() instead of min_t()
2025-11-19 22:41 ` [PATCH 18/44] drivers/gpio: use min() instead of min_t() david.laight.linux
@ 2025-11-20 8:01 ` Andy Shevchenko
2025-11-20 9:37 ` David Laight
0 siblings, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2025-11-20 8:01 UTC (permalink / raw)
To: david.laight.linux
Cc: linux-kernel, linux-acpi, linux-gpio, Bartosz Golaszewski,
Linus Walleij, Mika Westerberg
On Wed, Nov 19, 2025 at 10:41:14PM +0000, david.laight.linux@gmail.com wrote:
>
> min_t(u16, a, b) casts an 'unsigned long' to 'u16'.
> Use min(a, b) instead as it promotes the both values to int
> and so cannot discard significant bits.
>
> In this case the values should be ok.
>
> Detected by an extra check added to min_t().
In most of the patches you need to follow the commonly used Subject prefix.
This can be done by doing
git log --oneline --no-merges -- $FILE(S)_OF_INTEREST
For example,
$ git log --no-decorate --oneline --no-merges -- drivers/gpio/gpiolib-acpi*
b1055678a016 gpiolib: acpi: Use %pe when passing an error pointer to dev_err()
e4a77f9c85a5 gpiolib: acpi: Make set debounce errors non fatal
19c839a98c73 gpiolib: acpi: initialize acpi_gpio_info struct
3712ce9fa501 gpiolib: acpi: Ignore touchpad wakeup on GPD G1619-05
16c07342b542 gpiolib: acpi: Program debounce when finding GPIO
23800ad1265f gpiolib: acpi: Add quirk for ASUS ProArt PX13
...
> acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
> - length = min_t(u16, agpio->pin_table_length, pin_index + bits);
> + length = min(agpio->pin_table_length, pin_index + bits);
Now, if you look closer at the code, the pin_index alone has the problem you
are targeting here. On top of that the iterator and 'length' are signed, while
the result of min_t(u16) is unsigned (however it has no difference in this case).
...
TL;DR: I apply this patch with subject changed, but I think more work needs to
be done if you want to fix it fully.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 18/44] drivers/gpio: use min() instead of min_t()
2025-11-20 8:01 ` Andy Shevchenko
@ 2025-11-20 9:37 ` David Laight
0 siblings, 0 replies; 7+ messages in thread
From: David Laight @ 2025-11-20 9:37 UTC (permalink / raw)
To: Andy Shevchenko
Cc: linux-kernel, linux-acpi, linux-gpio, Bartosz Golaszewski,
Linus Walleij, Mika Westerberg
On Thu, 20 Nov 2025 10:01:29 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> On Wed, Nov 19, 2025 at 10:41:14PM +0000, david.laight.linux@gmail.com wrote:
> >
> > min_t(u16, a, b) casts an 'unsigned long' to 'u16'.
> > Use min(a, b) instead as it promotes the both values to int
> > and so cannot discard significant bits.
> >
> > In this case the values should be ok.
> >
> > Detected by an extra check added to min_t().
>
> In most of the patches you need to follow the commonly used Subject prefix.
> This can be done by doing
I did look up quite a few files to see what had been used previously.
But it is a bit tedious with 44 patches.
> git log --oneline --no-merges -- $FILE(S)_OF_INTEREST
I wasn't aware of that spell :-)
...
>
> > acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
>
> > - length = min_t(u16, agpio->pin_table_length, pin_index + bits);
> > + length = min(agpio->pin_table_length, pin_index + bits);
>
> Now, if you look closer at the code, the pin_index alone has the problem you
> are targeting here.
The compiler warning happens because 'pin_index + bits' is 'int' and the compiler
doesn't know the value fits in 16 bits.
It should fit, but only if the caller passes in valid data.
> On top of that the iterator and 'length' are signed, while
> the result of min_t(u16) is unsigned (however it has no difference in this case).
Actually the result type of min_t(u16) is 'int' (:? promotes char/short to int).
So the u16 cast does '(pin_index + bits) & 0xffff', everything is then promoted
to 'int' for all the comparisons (etc).
David
>
> ...
>
> TL;DR: I apply this patch with subject changed, but I think more work needs to
> be done if you want to fix it fully.
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 18/44] drivers/gpio: use min() instead of min_t() david.laight.linux
@ 2025-11-20 1:47 ` Jakub Kicinski
2025-11-20 9:38 ` Lorenzo Stoakes
2025-11-20 14:52 ` (subset) " Jens Axboe
3 siblings, 0 replies; 7+ messages in thread
From: Jakub Kicinski @ 2025-11-20 1:47 UTC (permalink / raw)
To: david.laight.linux
Cc: linux-kernel, 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 König, 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, Herbert Xu,
Ingo Molnar, 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,
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, Yury Norov, amd-gfx, bpf,
cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
linux-pci, linux-perf-users, linux-scsi, linux-serial,
linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage
On Wed, 19 Nov 2025 22:40:56 +0000 david.laight.linux@gmail.com wrote:
> 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.
Please split the networking (9?) patches out to a separate series.
It will help you with the CC list, and help us to get this applied..
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 18/44] drivers/gpio: use min() instead of min_t() david.laight.linux
2025-11-20 1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
@ 2025-11-20 9:38 ` Lorenzo Stoakes
2025-11-20 14:52 ` (subset) " Jens Axboe
3 siblings, 0 replies; 7+ messages in thread
From: Lorenzo Stoakes @ 2025-11-20 9:38 UTC (permalink / raw)
To: david.laight.linux
Cc: linux-kernel, 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 König, 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, Herbert Xu,
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,
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, Yury Norov, amd-gfx, bpf,
cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
linux-pci, linux-perf-users, linux-scsi, linux-serial,
linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage
On Wed, Nov 19, 2025 at 10:40:56PM +0000, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
>
> 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().)
Have we made sure that the introduction of these don't cause a combinatorial
explosion like previous min()/max() changes did?
>
> 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.
Well I have a beefy box at my disposal so tried thiese for you :)
Both allyesconfig & allmodconfig works fine for x86-64 (I tried both for good
measure)
> 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 guess this isn't broken per se there just retain min_t()/max_t() right?
>
> 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(-)
>
> --
> 2.39.5
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: (subset) [PATCH 00/44] Change a lot of min_t() that might mask high bits
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
` (2 preceding siblings ...)
2025-11-20 9:38 ` Lorenzo Stoakes
@ 2025-11-20 14:52 ` Jens Axboe
3 siblings, 0 replies; 7+ messages in thread
From: Jens Axboe @ 2025-11-20 14:52 UTC (permalink / raw)
To: linux-kernel, david.laight.linux
Cc: 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 König, Christoph Hellwig, Daniel Borkmann,
Dan Williams, Dave Hansen, Dave Jiang, David Ahern,
Davidlohr Bueso, David S. Miller, Dennis Zhou, Eric Dumazet,
Greg Kroah-Hartman, Herbert Xu, Ingo Molnar, Jakub Kicinski,
Jakub Sitnicki, James E.J. Bottomley, Jarkko Sakkinen,
Jason A. Donenfeld, 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, 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, Yury Norov,
amd-gfx, bpf, cgroups, dri-devel, io-uring, kvm, linux-acpi,
linux-block, linux-crypto, linux-cxl, linux-efi, linux-ext4,
linux-fsdevel, linux-gpio, linux-i2c, linux-integrity, linux-mm,
linux-nvme, linux-pci, linux-perf-users, linux-scsi, linux-serial,
linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage,
David Hildenbrand
On Wed, 19 Nov 2025 22:40:56 +0000, david.laight.linux@gmail.com wrote:
> 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.
>
> [...]
Applied, thanks!
[12/44] block: use min() instead of min_t()
commit: 9420e720ad192c53c8d2803c5a2313b2d586adbd
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 7+ messages in thread