linux.git/kernel/sysctl.c, branch v6.6.132

sysctl: fix uninitialized variable in proc_do_large_bitmap

2026-04-02T11:07:23+00:00

[ Upstream commit f63a9df7e3f9f842945d292a19d9938924f066f9 ]

proc_do_large_bitmap() does not initialize variable c, which is expected
to be set to a trailing character by proc_get_long().

However, proc_get_long() only sets c when the input buffer contains a
trailing character after the parsed value.

If c is not initialized it may happen to contain a '-'. If this is the
case proc_do_large_bitmap() expects to be able to parse a second part of
the input buffer. If there is no second part an unjustified -EINVAL will
be returned.

Initialize c to 0 to prevent returning -EINVAL on valid input.

Fixes: 9f977fb7ae9d ("sysctl: add proc_do_large_bitmap")
Signed-off-by: Marc Buerg 
Reviewed-by: Joel Granados 
Signed-off-by: Joel Granados 
Signed-off-by: Sasha Levin

Merge tag 'v6.5-rc1-sysctl-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2023-06-28T23:05:21+00:00

Pull sysctl updates from Luis Chamberlain:
 "The changes for sysctl are in line with prior efforts to stop usage of
  deprecated routines which incur recursion and also make it hard to
  remove the empty array element in each sysctl array declaration.

  The most difficult user to modify was parport which required a bit of
  re-thinking of how to declare shared sysctls there, Joel Granados has
  stepped up to the plate to do most of this work and eventual removal
  of register_sysctl_table(). That work ended up saving us about 1465
  bytes according to bloat-o-meter. Since we gained a few bloat-o-meter
  karma points I moved two rather small sysctl arrays from
  kernel/sysctl.c leaving us only two more sysctl arrays to move left.

  Most changes have been tested on linux-next for about a month. The
  last straggler patches are a minor parport fix, changes to the sysctl
  kernel selftest so to verify correctness and prevent regressions for
  the future change he made to provide an alternative solution for the
  special sysctl mount point target which was using the now deprecated
  sysctl child element.

  This is all prep work to now finally be able to remove the empty array
  element in all sysctl declarations / registrations which is expected
  to save us a bit of bytes all over the kernel. That work will be
  tested early after v6.5-rc1 is out"

* tag 'v6.5-rc1-sysctl-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: replace child with an enumeration
  sysctl: Remove debugging dump_stack
  test_sysclt: Test for registering a mount point
  test_sysctl: Add an option to prevent test skip
  test_sysctl: Add an unregister sysctl test
  test_sysctl: Group node sysctl test under one func
  test_sysctl: Fix test metadata getters
  parport: plug a sysctl register leak
  sysctl: move security keys sysctl registration to its own file
  sysctl: move umh sysctl registration to its own file
  signal: move show_unhandled_signals sysctl to its own file
  sysctl: remove empty dev table
  sysctl: Remove register_sysctl_table
  sysctl: Refactor base paths registrations
  sysctl: stop exporting register_sysctl_table
  parport: Removed sysctl related defines
  parport: Remove register_sysctl_table from parport_default_proc_register
  parport: Remove register_sysctl_table from parport_device_proc_register
  parport: Remove register_sysctl_table from parport_proc_register
  parport: Move magic number "15" to a define

mm: page_alloc: move sysctls into it own fils

2023-06-09T23:25:24+00:00

This moves all page alloc related sysctls to its own file, as part of the
kernel/sysctl.c spring cleaning, also move some functions declarations
from mm.h into internal.h.

Link: https://lkml.kernel.org/r/20230516063821.121844-13-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Cc: David Hildenbrand 
Cc: "Huang, Ying" 
Cc: Iurii Zaikin 
Cc: Kees Cook 
Cc: Len Brown 
Cc: Luis Chamberlain 
Cc: Mike Rapoport (IBM) 
Cc: Oscar Salvador 
Cc: Pavel Machek 
Cc: Rafael J. Wysocki 
Signed-off-by: Andrew Morton

sysctl: move security keys sysctl registration to its own file

2023-06-08T22:42:02+00:00

The security keys sysctls are already declared on its own file,
just move the sysctl registration to its own file to help avoid
merge conflicts on sysctls.c, and help with clearing up sysctl.c
further.

This creates a small penalty of 23 bytes:

./scripts/bloat-o-meter vmlinux.1 vmlinux.2
add/remove: 2/0 grow/shrink: 0/1 up/down: 49/-26 (23)
Function                                     old     new   delta
init_security_keys_sysctls                     -      33     +33
__pfx_init_security_keys_sysctls               -      16     +16
sysctl_init_bases                             85      59     -26
Total: Before=21256937, After=21256960, chg +0.00%

But soon we'll be saving tons of bytes anyway, as we modify the
sysctl registrations to use ARRAY_SIZE and so we get rid of all the
empty array elements so let's just clean this up now.

Reviewed-by: Paul Moore 
Acked-by: Jarkko Sakkinen 
Acked-by: David Howells 
Signed-off-by: Luis Chamberlain

sysctl: move umh sysctl registration to its own file

2023-06-08T22:41:34+00:00

Move the umh sysctl registration to its own file, the array is
already there. We do this to remove the clutter out of kernel/sysctl.c
to avoid merge conflicts.

This also lets the sysctls not be built at all now when CONFIG_SYSCTL
is not enabled.

This has a small penalty of 23 bytes but soon we'll be removing
all the empty entries on sysctl arrays so just do this cleanup
now:

./scripts/bloat-o-meter vmlinux.base vmlinux.1
add/remove: 2/0 grow/shrink: 0/1 up/down: 49/-26 (23)
Function                                     old     new   delta
init_umh_sysctls                               -      33     +33
__pfx_init_umh_sysctls                         -      16     +16
sysctl_init_bases                            111      85     -26
Total: Before=21256914, After=21256937, chg +0.00%

Acked-by: Jarkko Sakkinen 
Signed-off-by: Luis Chamberlain

signal: move show_unhandled_signals sysctl to its own file

2023-05-30T22:46:31+00:00

The show_unhandled_signals sysctl is the only sysctl for debug
left on kernel/sysctl.c. We've been moving the syctls out from
kernel/sysctl.c so to help avoid merge conflicts as the shared
array gets out of hand.

This change incurs simplifies sysctl registration by localizing
it where it should go for a penalty in size of increasing the
kernel by 23 bytes, we accept this given recent cleanups have
actually already saved us 1465 bytes in the prior commits.

./scripts/bloat-o-meter vmlinux.3-remove-dev-table vmlinux.4-remove-debug-table
add/remove: 3/1 grow/shrink: 0/1 up/down: 177/-154 (23)
Function                                     old     new   delta
signal_debug_table                             -     128    +128
init_signal_sysctls                            -      33     +33
__pfx_init_signal_sysctls                      -      16     +16
sysctl_init_bases                             85      59     -26
debug_table                                  128       -    -128
Total: Before=21256967, After=21256990, chg +0.00%

Reviewed-by: Joel Granados 
Signed-off-by: Luis Chamberlain

sysctl: remove empty dev table

2023-05-30T22:46:11+00:00

Now that all the dev sysctls have been moved out we can remove the
dev sysctl base directory. We don't need to create base directories,
they are created for you as if using 'mkdir -p' with register_syctl()
and register_sysctl_init(). For details refer to sysctl_mkdir_p()
usage.

We save 90 bytes with this changes:

./scripts/bloat-o-meter vmlinux.2.remove-sysctl-table vmlinux.3-remove-dev-table
add/remove: 0/1 grow/shrink: 0/1 up/down: 0/-90 (-90)
Function                                     old     new   delta
sysctl_init_bases                            111      85     -26
dev_table                                     64       -     -64
Total: Before=21257057, After=21256967, chg -0.00%

The empty dev table has been in place since the v2.5.0 days because
back then ordering was essentialy. But later commit 7ec66d06362d
("sysctl: Stop requiring explicit management of sysctl directories"),
merged as of v3.4-rc1, the entire ordering of directories was replaced
by allowing sysctl directory autogeneration. This new mechanism
introduced on v3.4 allows for sysctl directories to automatically be
created for sysctl tables when they are needed and automatically removes
them when no sysctl tables use them. That commit also added a dedicated
struct ctl_dir as a new type for these autogenerated directories.

Reviewed-by: Joel Granados 
Signed-off-by: Luis Chamberlain

sysctl: Refactor base paths registrations

2023-05-24T04:43:26+00:00

This is part of the general push to deprecate register_sysctl_paths and
register_sysctl_table. The old way of doing this through
register_sysctl_base and DECLARE_SYSCTL_BASE macro is replaced with a
call to register_sysctl_init. The 5 base paths affected are: "kernel",
"vm", "debug", "dev" and "fs".

We remove the register_sysctl_base function and the DECLARE_SYSCTL_BASE
macro since they are no longer needed.

In order to quickly acertain that the paths did not actually change I
executed `find /proc/sys/ | sha1sum` and made sure that the sha was the
same before and after the commit.

We end up saving 563 bytes with this change:

./scripts/bloat-o-meter vmlinux.0.base vmlinux.1.refactor-base-paths
add/remove: 0/5 grow/shrink: 2/0 up/down: 77/-640 (-563)
Function                                     old     new   delta
sysctl_init_bases                             55     111     +56
init_fs_sysctls                               12      33     +21
vm_base_table                                128       -    -128
kernel_base_table                            128       -    -128
fs_base_table                                128       -    -128
dev_base_table                               128       -    -128
debug_base_table                             128       -    -128
Total: Before=21258215, After=21257652, chg -0.00%

[mcgrof: modified to use register_sysctl_init() over register_sysctl()
 and add bloat-o-meter stats]

Signed-off-by: Joel Granados 
Signed-off-by: Luis Chamberlain 
Tested-by: Stephen Rothwell 
Acked-by: Christian Brauner

mm: compaction: move compaction sysctl to its own file

2023-04-13T18:49:35+00:00

This moves all compaction sysctls to its own file.

Move sysctl to where the functionality truly belongs to improve
readability, reduce merge conflicts, and facilitate maintenance.

I use x86_defconfig and linux-next-20230327 branch
$ make defconfig;make all -jn
CONFIG_COMPACTION=y

add/remove: 1/0 grow/shrink: 1/1 up/down: 350/-256 (94)
Function                                     old     new   delta
vm_compaction                                  -     320    +320
kcompactd_init                               180     210     +30
vm_table                                    2112    1856    -256
Total: Before=21119987, After=21120081, chg +0.00%

Despite the addition of 94 bytes the patch still seems a worthwile
cleanup.

Link: https://lore.kernel.org/lkml/067f7347-ba10-5405-920c-0f5f985c84f4@suse.cz/
Signed-off-by: Minghao Chi 
Acked-by: Vlastimil Babka 
Signed-off-by: Luis Chamberlain

mm: memory-failure: Move memory failure sysctls to its own file

2023-04-13T18:49:35+00:00

The sysctl_memory_failure_early_kill and memory_failure_recovery
are only used in memory-failure.c, move them to its own file.

Acked-by: Naoya Horiguchi 
Signed-off-by: Kefeng Wang 
[mcgrof: fix by adding empty ctl entry, this caused a crash]
Signed-off-by: Luis Chamberlain