linux-stable.git/fs/proc, branch v6.6.37

fs/proc: fix softlockup in __read_vmcore

2024-06-21T12:38:41+00:00

commit 5cbcb62dddf5346077feb82b7b0c9254222d3445 upstream.

While taking a kernel core dump with makedumpfile on a larger system,
softlockup messages often appear.

While softlockup warnings can be harmless, they can also interfere with
things like RCU freeing memory, which can be problematic when the kdump
kexec image is configured with as little memory as possible.

Avoid the softlockup, and give things like work items and RCU a chance to
do their thing during __read_vmcore by adding a cond_resched.

Link: https://lkml.kernel.org/r/20240507091858.36ff767f@imladris.surriel.com
Signed-off-by: Rik van Riel 
Acked-by: Baoquan He 
Cc: Dave Young 
Cc: Vivek Goyal 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

mm: /proc/pid/smaps_rollup: avoid skipping vma after getting mmap_lock again

2024-06-16T11:47:42+00:00

commit 6d065f507d82307d6161ac75c025111fb8b08a46 upstream.

After switching smaps_rollup to use VMA iterator, searching for next entry
is part of the condition expression of the do-while loop.  So the current
VMA needs to be addressed before the continue statement.

Otherwise, with some VMAs skipped, userspace observed memory
consumption from /proc/pid/smaps_rollup will be smaller than the sum of
the corresponding fields from /proc/pid/smaps.

Link: https://lkml.kernel.org/r/20240523183531.2535436-1-yzhong@purestorage.com
Fixes: c4c84f06285e ("fs/proc/task_mmu: stop using linked list and highest_vm_end")
Signed-off-by: Yuanyuan Zhong 
Reviewed-by: Mohamed Khalfella 
Cc: David Hildenbrand 
Cc: Matthew Wilcox (Oracle) 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

mm/ksm: fix ksm_zero_pages accounting

2024-06-16T11:47:41+00:00

commit c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6 upstream.

We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.

So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.

Fix it by changing to use atomic_long_t, and the same case with the
mm->ksm_zero_pages.

Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e01d ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f0704 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou 
Acked-by: David Hildenbrand 
Cc: Andrea Arcangeli 
Cc: Hugh Dickins 
Cc: Ran Xiaokai 
Cc: Stefan Roesch 
Cc: xu xin 
Cc: Yang Yang 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

proc: Move fdinfo PTRACE_MODE_READ check into the inode .permission operation

2024-06-16T11:47:33+00:00

commit 0a960ba49869ebe8ff859d000351504dd6b93b68 upstream.

The following commits loosened the permissions of /proc//fdinfo/
directory, as well as the files within it, from 0500 to 0555 while also
introducing a PTRACE_MODE_READ check between the current task and
's task:

 - commit 7bc3fa0172a4 ("procfs: allow reading fdinfo with PTRACE_MODE_READ")
 - commit 1927e498aee1 ("procfs: prevent unprivileged processes accessing fdinfo dir")

Before those changes, inode based system calls like inotify_add_watch(2)
would fail when the current task didn't have sufficient read permissions:

 [...]
 lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0500, st_size=0, ...}) = 0
 inotify_add_watch(64, "/proc/1/task/1/fdinfo",
		   IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
		   IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = -1 EACCES (Permission denied)
 [...]

This matches the documented behavior in the inotify_add_watch(2) man
page:

 ERRORS
       EACCES Read access to the given file is not permitted.

After those changes, inotify_add_watch(2) started succeeding despite the
current task not having PTRACE_MODE_READ privileges on the target task:

 [...]
 lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
 inotify_add_watch(64, "/proc/1/task/1/fdinfo",
		   IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
		   IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = 1757
 openat(AT_FDCWD, "/proc/1/task/1/fdinfo",
	O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 EACCES (Permission denied)
 [...]

This change in behavior broke .NET prior to v7. See the github link
below for the v7 commit that inadvertently/quietly (?) fixed .NET after
the kernel changes mentioned above.

Return to the old behavior by moving the PTRACE_MODE_READ check out of
the file .open operation and into the inode .permission operation:

 [...]
 lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
 inotify_add_watch(64, "/proc/1/task/1/fdinfo",
		   IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
		   IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = -1 EACCES (Permission denied)
 [...]

Reported-by: Kevin Parsons (Microsoft) 
Link: https://github.com/dotnet/runtime/commit/89e5469ac591b82d38510fe7de98346cce74ad4f
Link: https://stackoverflow.com/questions/75379065/start-self-contained-net6-build-exe-as-service-on-raspbian-system-unauthorizeda
Fixes: 7bc3fa0172a4 ("procfs: allow reading fdinfo with PTRACE_MODE_READ")
Cc: stable@vger.kernel.org
Cc: Christian Brauner 
Cc: Christian König 
Cc: Jann Horn 
Cc: Kalesh Singh 
Cc: Hardik Garg 
Cc: Allen Pais 
Signed-off-by: Tyler Hicks (Microsoft) 
Link: https://lore.kernel.org/r/20240501005646.745089-1-code@tyhicks.com
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

mm: support page_mapcount() on page_has_type() pages

2024-05-02T14:32:43+00:00

commit fd1a745ce03e37945674c14833870a9af0882e2d upstream.

Return 0 for pages which can't be mapped.  This matches how page_mapped()
works.  It is more convenient for users to not have to filter out these
pages.

Link: https://lkml.kernel.org/r/20240321142448.1645400-5-willy@infradead.org
Fixes: 9c5ccf2db04b ("mm: remove HUGETLB_PAGE_DTOR")
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: David Hildenbrand 
Acked-by: Vlastimil Babka 
Cc: Miaohe Lin 
Cc: Muchun Song 
Cc: Oscar Salvador 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

fs/proc: do_task_stat: move thread_group_cputime_adjusted() outside of lock_task_sighand()

2024-02-23T08:25:17+00:00

commit 60f92acb60a989b14e4b744501a0df0f82ef30a3 upstream.

Patch series "fs/proc: do_task_stat: use sig->stats_".

do_task_stat() has the same problem as getrusage() had before "getrusage:
use sig->stats_lock rather than lock_task_sighand()": a hard lockup.  If
NR_CPUS threads call lock_task_sighand() at the same time and the process
has NR_THREADS, spin_lock_irq will spin with irqs disabled O(NR_CPUS *
NR_THREADS) time.


This patch (of 3):

thread_group_cputime() does its own locking, we can safely shift
thread_group_cputime_adjusted() which does another for_each_thread loop
outside of ->siglock protected section.

Not only this removes for_each_thread() from the critical section with
irqs disabled, this removes another case when stats_lock is taken with
siglock held.  We want to remove this dependency, then we can change the
users of stats_lock to not disable irqs.

Link: https://lkml.kernel.org/r/20240123153313.GA21832@redhat.com
Link: https://lkml.kernel.org/r/20240123153355.GA21854@redhat.com
Signed-off-by: Oleg Nesterov 
Signed-off-by: Dylan Hatch 
Cc: Eric W. Biederman 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

sysctl: Fix out of bounds access for empty sysctl registers

2024-02-05T20:14:17+00:00

[ Upstream commit 315552310c7de92baea4e570967066569937a843 ]

When registering tables to the sysctl subsystem there is a check to see
if header is a permanently empty directory (used for mounts). This check
evaluates the first element of the ctl_table. This results in an out of
bounds evaluation when registering empty directories.

The function register_sysctl_mount_point now passes a ctl_table of size
1 instead of size 0. It now relies solely on the type to identify
a permanently empty register.

Make sure that the ctl_table has at least one element before testing for
permanent emptiness.

Signed-off-by: Joel Granados 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-lkp/202311201431.57aae8f3-oliver.sang@intel.com
Signed-off-by: Luis Chamberlain 
Signed-off-by: Sasha Levin

watchdog: move softlockup_panic back to early_param

2023-11-28T17:19:57+00:00

commit 8b793bcda61f6c3ed4f5b2ded7530ef6749580cb upstream.

Setting softlockup_panic from do_sysctl_args() causes it to take effect
later in boot.  The lockup detector is enabled before SMP is brought
online, but do_sysctl_args runs afterwards.  If a user wants to set
softlockup_panic on boot and have it trigger should a softlockup occur
during onlining of the non-boot processors, they could do this prior to
commit f117955a2255 ("kernel/watchdog.c: convert {soft/hard}lockup boot
parameters to sysctl aliases").  However, after this commit the value
of softlockup_panic is set too late to be of help for this type of
problem.  Restore the prior behavior.

Signed-off-by: Krister Johansen 
Cc: stable@vger.kernel.org
Fixes: f117955a2255 ("kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases")
Signed-off-by: Luis Chamberlain 
Signed-off-by: Greg Kroah-Hartman

proc: sysctl: prevent aliased sysctls from getting passed to init

2023-11-28T17:19:57+00:00

commit 8001f49394e353f035306a45bcf504f06fca6355 upstream.

The code that checks for unknown boot options is unaware of the sysctl
alias facility, which maps bootparams to sysctl values.  If a user sets
an old value that has a valid alias, a message about an invalid
parameter will be printed during boot, and the parameter will get passed
to init.  Fix by checking for the existence of aliased parameters in the
unknown boot parameter code.  If an alias exists, don't return an error
or pass the value to init.

Signed-off-by: Krister Johansen 
Cc: stable@vger.kernel.org
Fixes: 0a477e1ae21b ("kernel/sysctl: support handling command line aliases")
Signed-off-by: Luis Chamberlain 
Signed-off-by: Greg Kroah-Hartman

proc: nommu: fix empty /proc//maps

2023-09-19T20:21:34+00:00

On no-MMU, /proc//maps reads as an empty file.  This happens because
find_vma(mm, 0) always returns NULL (assuming no vma actually contains the
zero address, which is normally the case).

To fix this bug and improve the maintainability in the future, this patch
makes the no-MMU implementation as similar as possible to the MMU
implementation.

The only remaining differences are the lack of hold/release_task_mempolicy
and the extra code to shoehorn the gate vma into the iterator.

This has been tested on top of 6.5.3 on an STM32F746.

Link: https://lkml.kernel.org/r/20230915160055.971059-2-ben.wolsieffer@hefring.com
Fixes: 0c563f148043 ("proc: remove VMA rbtree use from nommu")
Signed-off-by: Ben Wolsieffer 
Cc: Davidlohr Bueso 
Cc: Giulio Benetti 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Oleg Nesterov 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton