linux.git/arch/x86/kernel/dumpstack.c, branch v6.6

x86/show_trace_log_lvl: Ensure stack pointer is aligned, again

2023-05-16T13:31:04+00:00

The commit e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned")
tried to align the stack pointer in show_trace_log_lvl(), otherwise the
"stack < stack_info.end" check can't guarantee that the last read does
not go past the end of the stack.

However, we have the same problem with the initial value of the stack
pointer, it can also be unaligned. So without this patch this trivial
kernel module

	#include 

	static int init(void)
	{
		asm volatile("sub    $0x4,%rsp");
		dump_stack();
		asm volatile("add    $0x4,%rsp");

		return -EAGAIN;
	}

	module_init(init);
	MODULE_LICENSE("GPL");

crashes the kernel.

Fixes: e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned")
Signed-off-by: Vernon Lovejoy 
Signed-off-by: Oleg Nesterov 
Link: https://lore.kernel.org/r/20230512104232.GA10227@redhat.com
Signed-off-by: Josh Poimboeuf

Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-11T00:53:04+00:00

Pull MM updates from Andrew Morton:

- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).

- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.

Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.

Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.

- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.

KMSAN keeps finding bugs. New ones, as well as the legacy ones.

- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.

- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.

- userfaultfd updates from Axel Rasmussen

- zsmalloc cleanups from Alexey Romanov

- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure

- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.

- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.

- memcg cleanups from Kairui Song.

- memcg fixes and cleanups from Johannes Weiner.

- Vishal Moola provides more folio conversions

- Zhang Yi removed ll_rw_block() :(

- migration enhancements from Peter Xu

- migration error-path bugfixes from Huang Ying

- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.

- vma merging improvements from Jakub Matěn.

- NUMA hinting cleanups from David Hildenbrand.

- xu xin added aditional userspace visibility into KSM merging
activity.

- THP & KSM code consolidation from Qi Zheng.

- more folio work from Matthew Wilcox.

- KASAN updates from Andrey Konovalov.

- DAMON cleanups from Kaixu Xia.

- DAMON work from SeongJae Park: fixes, cleanups.

- hugetlb sysfs cleanups from Muchun Song.

- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.

Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]

* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...

x86: kmsan: don't instrument stack walking functions

2022-10-03T21:03:25+00:00

Upon function exit, KMSAN marks local variables as uninitialized.  Further
function calls may result in the compiler creating the stack frame where
these local variables resided.  This results in frame pointers being
marked as uninitialized data, which is normally correct, because they are
not stack-allocated.

However stack unwinding functions are supposed to read and dereference the
frame pointers, in which case KMSAN might be reporting uses of
uninitialized values.

To work around that, we mark update_stack_state(), unwind_next_frame() and
show_trace_log_lvl() with __no_kmsan_checks, preventing all KMSAN reports
inside those functions and making them return initialized values.

Link: https://lkml.kernel.org/r/20220915150417.722975-40-glider@google.com
Signed-off-by: Alexander Potapenko 
Cc: Alexander Viro 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Konovalov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Christoph Hellwig 
Cc: Christoph Lameter 
Cc: David Rientjes 
Cc: Dmitry Vyukov 
Cc: Eric Biggers 
Cc: Eric Biggers 
Cc: Eric Dumazet 
Cc: Greg Kroah-Hartman 
Cc: Herbert Xu 
Cc: Ilya Leoshkevich 
Cc: Ingo Molnar 
Cc: Jens Axboe 
Cc: Joonsoo Kim 
Cc: Kees Cook 
Cc: Marco Elver 
Cc: Mark Rutland 
Cc: Matthew Wilcox 
Cc: Michael S. Tsirkin 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Stephen Rothwell 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vegard Nossum 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

x86/dumpstack: Don't mention RIP in "Code: "

2022-09-20T14:11:54+00:00

Commit

  238c91115cd0 ("x86/dumpstack: Fix misleading instruction pointer error message")

changed the "Code:" line in bug reports when RIP is an invalid pointer.
In particular, the report currently says (for example):

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  ...
  RIP: 0010:0x0
  Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.

That

  Unable to access opcode bytes at RIP 0xffffffffffffffd6.

is quite confusing as RIP value is 0, not -42. That -42 comes from
"regs->ip - PROLOGUE_SIZE", because Code is dumped with some prologue
(and epilogue).

So do not mention "RIP" on this line in this context.

Signed-off-by: Jiri Slaby 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/b772c39f-c5ae-8f17-fe6e-6a2bc4d1f83b@kernel.org

x86: remove __range_not_ok()

2022-02-25T08:36:05+00:00

The __range_not_ok() helper is an x86 (and sparc64) specific interface
that does roughly the same thing as __access_ok(), but with different
calling conventions.

Change this to use the normal interface in order for consistency as we
clean up all access_ok() implementations.

This changes the limit from TASK_SIZE to TASK_SIZE_MAX, which Al points
out is the right thing do do here anyway.

The callers have to use __access_ok() instead of the normal access_ok()
though, because on x86 that contains a WARN_ON_IN_IRQ() check that cannot
be used inside of NMI context while tracing.

The check in copy_code() is not needed any more, because this one is
already done by copy_from_user_nmi().

Suggested-by: Al Viro 
Suggested-by: Christoph Hellwig 
Link: https://lore.kernel.org/lkml/YgsUKcXGR7r4nINj@zeniv-ca.linux.org.uk/
Signed-off-by: Arnd Bergmann

exit: Add and use make_task_dead.

2021-12-13T18:04:45+00:00

There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman"

x86/dumpstack: use %pSb/%pBb for backtrace printing

2021-07-08T18:48:22+00:00

Let's use the new printk formats to print the stacktrace entries when
printing a backtrace to the kernel logs.  This will include any module's
build ID[1] in it so that offline/crash debugging can easily locate the
debuginfo for a module via something like debuginfod[2].

Link: https://lkml.kernel.org/r/20210511003845.2429846-8-swboyd@chromium.org
Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1]
Link: https://sourceware.org/elfutils/Debuginfod.html [2]
Signed-off-by: Stephen Boyd 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Andy Shevchenko 
Cc: Matthew Wilcox 
Cc: Baoquan He 
Cc: Catalin Marinas 
Cc: Dave Young 
Cc: Konstantin Khlebnikov 
Cc: Rasmus Villemoes 
Cc: Sasha Levin 
Cc: Sergey Senozhatsky 
Cc: Vivek Goyal 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-12-14T21:45:26+00:00

Pull x86 cleanups from Borislav Petkov:
 "Another branch with a nicely negative diffstat, just the way I
  like 'em:

   - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in
     the end (Gabriel Krisman Bertazi)

   - All kinds of minor cleanups all over the tree"

* tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/ia32_signal: Propagate __user annotation properly
  x86/alternative: Update text_poke_bp() kernel-doc comment
  x86/PCI: Make a kernel-doc comment a normal one
  x86/asm: Drop unused RDPID macro
  x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg
  x86/head64: Remove duplicate include
  x86/mm: Declare 'start' variable where it is used
  x86/head/64: Remove unused GET_CR2_INTO() macro
  x86/boot: Remove unused finalize_identity_maps()
  x86/uaccess: Document copy_from_user_nmi()
  x86/dumpstack: Make show_trace_log_lvl() static
  x86/mtrr: Fix a kernel-doc markup
  x86/setup: Remove unused MCA variables
  x86, libnvdimm/test: Remove COPY_MC_TEST
  x86: Reclaim TIF_IA32 and TIF_X32
  x86/mm: Convert mmu context ia32_compat into a proper flags field
  x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages()
  elf: Expose ELF header on arch_setup_additional_pages()
  x86/elf: Use e_machine to select start_thread for x32
  elf: Expose ELF header in compat_start_thread()
  ...

x86/dumpstack: Do not try to access user space code of other tasks

2020-11-18T11:56:29+00:00

sysrq-t ends up invoking show_opcodes() for each task which tries to access
the user space code of other processes, which is obviously bogus.

It either manages to dump where the foreign task's regs->ip points to in a
valid mapping of the current task or triggers a pagefault and prints "Code:
Bad RIP value.". Both is just wrong.

Add a safeguard in copy_code() and check whether the @regs pointer matches
currents pt_regs. If not, do not even try to access it.

While at it, add commentary why using copy_from_user_nmi() is safe in
copy_code() even if the function name suggests otherwise.

Reported-by: Oleg Nesterov 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Borislav Petkov 
Reviewed-by: Borislav Petkov 
Acked-by: Oleg Nesterov 
Tested-by: Borislav Petkov 
Link: https://lkml.kernel.org/r/20201117202753.667274723@linutronix.de

x86/dumpstack: Make show_trace_log_lvl() static

2020-11-17T18:05:32+00:00

show_trace_log_lvl() is not used by other compilation units so make it
static and remove the declaration from the header file.

Signed-off-by: Hui Su 
Signed-off-by: Borislav Petkov 
Link: https://lkml.kernel.org/r/20201113133943.GA136221@rlk