linux-stable.git/fs/proc, branch v6.6.78

fs/proc: do_task_stat: Fix ESP not readable during coredump

2025-02-17T08:40:15+00:00

commit ab251dacfbae28772c897f068a4184f478189ff2 upstream.

The field "eip" (instruction pointer) and "esp" (stack pointer) of a task
can be read from /proc/PID/stat. These fields can be interesting for
coredump.

However, these fields were disabled by commit 0a1eb2d474ed ("fs/proc: Stop
reporting eip and esp in /proc/PID/stat"), because it is generally unsafe
to do so. But it is safe for a coredumping process, and therefore
exceptions were made:

  - for a coredumping thread by commit fd7d56270b52 ("fs/proc: Report
    eip/esp in /prod/PID/stat for coredumping").

  - for all other threads in a coredumping process by commit cb8f381f1613
    ("fs/proc/array.c: allow reporting eip/esp for all coredumping
    threads").

The above two commits check the PF_DUMPCORE flag to determine a coredump thread
and the PF_EXITING flag for the other threads.

Unfortunately, commit 92307383082d ("coredump:  Don't perform any cleanups
before dumping core") moved coredump to happen earlier and before PF_EXITING is
set. Thus, checking PF_EXITING is no longer the correct way to determine
threads in a coredumping process.

Instead of PF_EXITING, use PF_POSTCOREDUMP to determine the other threads.

Checking of PF_EXITING was added for coredumping, so it probably can now be
removed. But it doesn't hurt to keep.

Fixes: 92307383082d ("coredump:  Don't perform any cleanups before dumping core")
Cc: stable@vger.kernel.org
Cc: Eric W. Biederman 
Acked-by: Oleg Nesterov 
Acked-by: Kees Cook 
Signed-off-by: Nam Cao 
Link: https://lore.kernel.org/r/d89af63d478d6c64cc46a01420b46fd6eb147d6f.1735805772.git.namcao@linutronix.de
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

fs/proc: fix softlockup in __read_vmcore (part 2)

2025-01-23T16:21:16+00:00

commit cbc5dde0a461240046e8a41c43d7c3b76d5db952 upstream.

Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the
number of softlockups in __read_vmcore at kdump time have gone down, but
they still happen sometimes.

In a memory constrained environment like the kdump image, a softlockup is
not just a harmless message, but it can interfere with things like RCU
freeing memory, causing the crashdump to get stuck.

The second loop in __read_vmcore has a lot more opportunities for natural
sleep points, like scheduling out while waiting for a data write to
happen, but apparently that is not always enough.

Add a cond_resched() to the second loop in __read_vmcore to (hopefully)
get rid of the softlockups.

Link: https://lkml.kernel.org/r/20250110102821.2a37581b@fangorn
Fixes: 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore")
Signed-off-by: Rik van Riel 
Reported-by: Breno Leitao 
Cc: Baoquan He 
Cc: Dave Young 
Cc: Vivek Goyal 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

fs/proc/task_mmu: fix pagemap flags with PMD THP entries on 32bit

2025-01-09T12:32:08+00:00

commit 3754137d263f52f4b507cf9ae913f8f0497d1b0e upstream.

Entries (including flags) are u64, even on 32bit.  So right now we are
cutting of the flags on 32bit.  This way, for example the cow selftest
complains about:

  # ./cow
  ...
  Bail Out! read and ioctl return unmatched results for populated: 0 1

Link: https://lkml.kernel.org/r/20241217195000.1734039-1-david@redhat.com
Fixes: 2c1f057e5be6 ("fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs")
Signed-off-by: David Hildenbrand 
Cc: Oscar Salvador 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

2024-12-09T09:33:07+00:00

commit 088f294609d8f8816dc316681aef2eb61982e0da upstream.

If iov_iter_zero succeeds after failed copy_from_kernel_nofault,
we need to reset the ret value to zero otherwise it will be returned
as final return value of read_kcore_iter.

This fixes objdump -d dump over /proc/kcore for me.

Cc: stable@vger.kernel.org
Cc: Alexander Gordeev 
Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses")
Signed-off-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20241121231118.3212000-1-jolsa@kernel.org
Acked-by: Alexander Gordeev 
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: fix coccinelle reported ERROR instances

2024-12-09T09:32:18+00:00

[ Upstream commit 82e33f249f1126cf3c5f39a31b850d485ac33bc3 ]

Coccinelle complains about the nested reuse of the pointer `iter' with
different pointer type:

./fs/proc/kcore.c:515:26-30: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:534:23-27: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:550:40-44: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:568:27-31: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:581:28-32: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:599:27-31: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:607:38-42: ERROR: invalid reference to the index variable of the iterator on line 499
./fs/proc/kcore.c:614:26-30: ERROR: invalid reference to the index variable of the iterator on line 499

Replacing `struct kcore_list *iter' with `struct kcore_list *tmp' doesn't change the
scope and the functionality is the same and coccinelle seems happy.

NOTE: There was an issue with using `struct kcore_list *pos' as the nested iterator.
      The build did not work!

[akpm@linux-foundation.org: s/tmp/pos/]
Link: https://lkml.kernel.org/r/20241029054651.86356-2-mtodorovac69@gmail.com
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Link: https://lkml.kernel.org/r/20220331223700.902556-1-jakobkoschel@gmail.com
Fixes: 04d168c6d42d ("fs/proc/kcore.c: remove check of list iterator against head past the loop body")
Signed-off-by: Jakob Koschel 
Signed-off-by: Mirsad Todorovac 
Cc: Mike Rapoport 
Cc: David Hildenbrand 
Cc: Oscar Salvador 
Cc: "Brian Johannesmeyer" 
Cc: Cristiano Giuffrida 
Cc: "Bos, H.J." 
Cc: Alexey Dobriyan 
Cc: Andrew Morton 
Cc: Yang Li 
Cc: Baoquan He 
Cc: Hari Bathini 
Cc: Yan Zhen 
Cc: Alexander Gordeev 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats

2024-12-09T09:31:41+00:00

[ Upstream commit 7601df8031fd67310af891897ef6cc0df4209305 ]

lock_task_sighand() can trigger a hard lockup.  If NR_CPUS threads call
do_task_stat() at the same time and the process has NR_THREADS, it will
spin with irqs disabled O(NR_CPUS * NR_THREADS) time.

Change do_task_stat() to use sig->stats_lock to gather the statistics
outside of ->siglock protected section, in the likely case this code will
run lockless.

Link: https://lkml.kernel.org/r/20240123153357.GA21857@redhat.com
Signed-off-by: Oleg Nesterov 
Signed-off-by: Dylan Hatch 
Cc: Eric W. Biederman 
Cc: 
Signed-off-by: Andrew Morton 
[ Resolve minor conflicts ]
Signed-off-by: Bin Lan 
Signed-off-by: Sasha Levin

proc/softirqs: replace seq_printf with seq_put_decimal_ull_width

2024-12-09T09:31:39+00:00

[ Upstream commit 84b9749a3a704dcc824a88aa8267247c801d51e4 ]

seq_printf is costy, on a system with n CPUs, reading /proc/softirqs
would yield 10*n decimal values, and the extra cost parsing format string
grows linearly with number of cpus. Replace seq_printf with
seq_put_decimal_ull_width have significant performance improvement.
On an 8CPUs system, reading /proc/softirqs show ~40% performance
gain with this patch.

Signed-off-by: David Wang <00107082@163.com>
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

fs/proc: fix compile warning about variable 'vmcore_mmap_ops'

2024-11-14T12:19:39+00:00

commit b8ee299855f08539e04d6c1a6acb3dc9e5423c00 upstream.

When build with !CONFIG_MMU, the variable 'vmcore_mmap_ops'
is defined but not used:

>> fs/proc/vmcore.c:458:42: warning: unused variable 'vmcore_mmap_ops'
     458 | static const struct vm_operations_struct vmcore_mmap_ops = {

Fix this by only defining it when CONFIG_MMU is enabled.

Link: https://lkml.kernel.org/r/20241101034803.9298-1-xiqi2@huawei.com
Fixes: 9cb218131de1 ("vmcore: introduce remap_oldmem_pfn_range()")
Signed-off-by: Qi Xi 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/lkml/202410301936.GcE8yUos-lkp@intel.com/
Cc: Baoquan He 
Cc: Dave Young 
Cc: Michael Holzheu 
Cc: Vivek Goyal 
Cc: Wang ShaoBo 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: allow translation of physical memory addresses

2024-10-17T13:24:37+00:00

commit 3d5854d75e3187147613130561b58f0b06166172 upstream.

When /proc/kcore is read an attempt to read the first two pages results in
HW-specific page swap on s390 and another (so called prefix) pages are
accessed instead.  That leads to a wrong read.

Allow architecture-specific translation of memory addresses using
kc_xlate_dev_mem_ptr() and kc_unxlate_dev_mem_ptr() callbacks similarily
to /dev/mem xlate_dev_mem_ptr() and unxlate_dev_mem_ptr() callbacks.  That
way an architecture can deal with specific physical memory ranges.

Re-use the existing /dev/mem callback implementation on s390, which
handles the described prefix pages swapping correctly.

For other architectures the default callback is basically NOP.  It is
expected the condition (vaddr == __va(__pa(vaddr))) always holds true for
KCORE_RAM memory type.

Link: https://lkml.kernel.org/r/20240930122119.1651546-1-agordeev@linux.ibm.com
Signed-off-by: Alexander Gordeev 
Suggested-by: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

proc: add config & param to block forcing mem writes

2024-10-10T09:57:27+00:00

[ Upstream commit 41e8149c8892ed1962bd15350b3c3e6e90cba7f4 ]

This adds a Kconfig option and boot param to allow removing
the FOLL_FORCE flag from /proc/pid/mem write calls because
it can be abused.

The traditional forcing behavior is kept as default because
it can break GDB and some other use cases.

Previously we tried a more sophisticated approach allowing
distributions to fine-tune /proc/pid/mem behavior, however
that got NAK-ed by Linus [1], who prefers this simpler
approach with semantics also easier to understand for users.

Link: https://lore.kernel.org/lkml/CAHk-=wiGWLChxYmUA5HrT5aopZrB7_2VTa0NLZcxORgkUe5tEQ@mail.gmail.com/ [1]
Cc: Doug Anderson 
Cc: Jeff Xu 
Cc: Jann Horn 
Cc: Kees Cook 
Cc: Ard Biesheuvel 
Cc: Christian Brauner 
Suggested-by: Linus Torvalds 
Signed-off-by: Linus Torvalds 
Signed-off-by: Adrian Ratiu 
Link: https://lore.kernel.org/r/20240802080225.89408-1-adrian.ratiu@collabora.com
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin