linux-stable.git/mm/vmalloc.c, branch v4.14.331

mm/vmalloc.c: don't dereference possible NULL pointer in __vunmap()

2020-06-03T06:18:11+00:00

commit 6ade20327dbb808882888ed8ccded71e93067cf9 upstream.

find_vmap_area() can return a NULL pointer and we're going to
dereference it without checking it first.  Use the existing
find_vm_area() function which does exactly what we want and checks for
the NULL pointer.

Link: http://lkml.kernel.org/r/20181228171009.22269-1-liviu@dudau.co.uk
Fixes: f3c01d2f3ade ("mm: vmalloc: avoid racy handling of debugobjects in vunmap")
Signed-off-by: Liviu Dudau 
Reviewed-by: Andrew Morton 
Cc: Chintan Pandya 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Cc: Guenter Roeck 
Signed-off-by: Greg Kroah-Hartman

vmalloc: fix remap_vmalloc_range() bounds checks

2020-05-02T15:24:21+00:00

commit bdebd6a2831b6fab69eb85cee74a8ba77f1a1cc2 upstream.

remap_vmalloc_range() has had various issues with the bounds checks it
promises to perform ("This function checks that addr is a valid
vmalloc'ed area, and that it is big enough to cover the vma") over time,
e.g.:

 - not detecting pgoff<
Signed-off-by: Andrew Morton 
Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Martin KaFai Lau 
Cc: Song Liu 
Cc: Yonghong Song 
Cc: Andrii Nakryiko 
Cc: John Fastabend 
Cc: KP Singh 
Link: http://lkml.kernel.org/r/20200415222312.236431-1-jannh@google.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/vmalloc.c: move 'area->pages' after if statement

2020-04-24T06:01:00+00:00

commit 7ea362427c170061b8822dd41bafaa72b3bcb9ad upstream.

If !area->pages statement is true where memory allocation fails, area is
freed.

In this case 'area->pages = pages' should not executed.  So move
'area->pages = pages' after if statement.

[akpm@linux-foundation.org: give area->pages the same treatment]
Link: http://lkml.kernel.org/r/20190830035716.GA190684@LGEARND20B15
Signed-off-by: Austin Kim 
Acked-by: Michal Hocko 
Reviewed-by: Andrew Morton 
Cc: Uladzislau Rezki (Sony) 
Cc: Roman Gushchin 
Cc: Roman Penyaev 
Cc: Rick Edgecombe 
Cc: Mike Rapoport 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Lee Jones 
Signed-off-by: Greg Kroah-Hartman

x86/mm: split vmalloc_sync_all()

2020-04-02T14:34:20+00:00

commit 763802b53a427ed3cbd419dbba255c414fdd9e7c upstream.

Commit 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in
__purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in
the vunmap() code-path.  While this change was necessary to maintain
correctness on x86-32-pae kernels, it also adds additional cycles for
architectures that don't need it.

Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported
severe performance regressions in micro-benchmarks because it now also
calls the x86-64 implementation of vmalloc_sync_all() on vunmap().  But
the vmalloc_sync_all() implementation on x86-64 is only needed for newly
created mappings.

To avoid the unnecessary work on x86-64 and to gain the performance
back, split up vmalloc_sync_all() into two functions:

	* vmalloc_sync_mappings(), and
	* vmalloc_sync_unmappings()

Most call-sites to vmalloc_sync_all() only care about new mappings being
synchronized.  The only exception is the new call-site added in the
above mentioned commit.

Shile Zhang directed us to a report of an 80% regression in reaim
throughput.

Fixes: 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()")
Reported-by: kernel test robot 
Reported-by: Shile Zhang 
Signed-off-by: Joerg Roedel 
Signed-off-by: Andrew Morton 
Tested-by: Borislav Petkov 
Acked-by: Rafael J. Wysocki 	[GHES]
Cc: Dave Hansen 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: 
Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org
Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/
Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()

2019-08-16T08:13:48+00:00

commit 3f8fd02b1bf1d7ba964485a56f2f4b53ae88c167 upstream.

On x86-32 with PTI enabled, parts of the kernel page-tables are not shared
between processes. This can cause mappings in the vmalloc/ioremap area to
persist in some page-tables after the region is unmapped and released.

When the region is re-used the processes with the old mappings do not fault
in the new mappings but still access the old ones.

This causes undefined behavior, in reality often data corruption, kernel
oopses and panics and even spontaneous reboots.

Fix this problem by activly syncing unmaps in the vmalloc/ioremap area to
all page-tables in the system before the regions can be re-used.

References: https://bugzilla.suse.com/show_bug.cgi?id=1118689
Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F')
Signed-off-by: Joerg Roedel 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Dave Hansen 
Link: https://lkml.kernel.org/r/20190719184652.11391-4-joro@8bytes.org
Signed-off-by: Greg Kroah-Hartman

mm/vmalloc.c: fix kernel BUG at mm/vmalloc.c:512!

2019-04-05T20:31:27+00:00

[ Upstream commit afd07389d3f4933c7f7817a92fb5e053d59a3182 ]

One of the vmalloc stress test case triggers the kernel BUG():

  
  [60.562151] ------------[ cut here ]------------
  [60.562154] kernel BUG at mm/vmalloc.c:512!
  [60.562206] invalid opcode: 0000 [#1] PREEMPT SMP PTI
  [60.562247] CPU: 0 PID: 430 Comm: vmalloc_test/0 Not tainted 4.20.0+ #161
  [60.562293] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  [60.562351] RIP: 0010:alloc_vmap_area+0x36f/0x390
  

it can happen due to big align request resulting in overflowing of
calculated address, i.e.  it becomes 0 after ALIGN()'s fixup.

Fix it by checking if calculated address is within vstart/vend range.

Link: http://lkml.kernel.org/r/20190124115648.9433-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) 
Reviewed-by: Andrew Morton 
Cc: Ingo Molnar 
Cc: Joel Fernandes 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: Oleksiy Avramchenko 
Cc: Steven Rostedt 
Cc: Tejun Heo 
Cc: Thomas Garnier 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/vmalloc: fix size check for remap_vmalloc_range_partial()

2019-03-23T13:35:24+00:00

commit 401592d2e095947344e10ec0623adbcd58934dd4 upstream.

When VM_NO_GUARD is not set area->size includes adjacent guard page,
thus for correct size checking get_vm_area_size() should be used, but
not area->size.

This fixes possible kernel oops when userspace tries to mmap an area on
1 page bigger than was allocated by vmalloc_user() call: the size check
inside remap_vmalloc_range_partial() accounts non-existing guard page
also, so check successfully passes but vmalloc_to_page() returns NULL
(guard page does not physically exist).

The following code pattern example should trigger an oops:

  static int oops_mmap(struct file *file, struct vm_area_struct *vma)
  {
        void *mem;

        mem = vmalloc_user(4096);
        BUG_ON(!mem);
        /* Do not care about mem leak */

        return remap_vmalloc_range(vma, mem, 0);
  }

And userspace simply mmaps size + PAGE_SIZE:

  mmap(NULL, 8192, PROT_WRITE|PROT_READ, MAP_PRIVATE, fd, 0);

Possible candidates for oops which do not have any explicit size
checks:

   *** drivers/media/usb/stkwebcam/stk-webcam.c:
   v4l_stk_mmap[789]   ret = remap_vmalloc_range(vma, sbuf->buffer, 0);

Or the following one:

   *** drivers/video/fbdev/core/fbmem.c
   static int
   fb_mmap(struct file *file, struct vm_area_struct * vma)
        ...
        res = fb->fb_mmap(info, vma);

Where fb_mmap callback calls remap_vmalloc_range() directly without any
explicit checks:

   *** drivers/video/fbdev/vfb.c
   static int vfb_mmap(struct fb_info *info,
             struct vm_area_struct *vma)
   {
       return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
   }

Link: http://lkml.kernel.org/r/20190103145954.16942-2-rpenyaev@suse.de
Signed-off-by: Roman Penyaev 
Acked-by: Michal Hocko 
Cc: Andrey Ryabinin 
Cc: Joe Perches 
Cc: "Luis R. Rodriguez" 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: vmalloc: avoid racy handling of debugobjects in vunmap

2018-08-03T05:50:23+00:00

[ Upstream commit f3c01d2f3ade6790db67f80fef60df84424f8964 ]

Currently, __vunmap flow is,
 1) Release the VM area
 2) Free the debug objects corresponding to that vm area.

This leave some race window open.
 1) Release the VM area
 1.5) Some other client gets the same vm area
 1.6) This client allocates new debug objects on the same
      vm area
 2) Free the debug objects corresponding to this vm area.

Here, we actually free 'other' client's debug objects.

Fix this by freeing the debug objects first and then releasing the VM
area.

Link: http://lkml.kernel.org/r/1523961828-9485-2-git-send-email-cpandya@codeaurora.org
Signed-off-by: Chintan Pandya 
Reviewed-by: Andrew Morton 
Cc: Ard Biesheuvel 
Cc: Byungchul Park 
Cc: Catalin Marinas 
Cc: Florian Fainelli 
Cc: Johannes Weiner 
Cc: Laura Abbott 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Yisheng Xie 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems

2018-02-25T10:08:04+00:00

commit 698d0831ba87b92ae10b15e8203cfd59f5a59a35 upstream.

Kai Heng Feng has noticed that BUG_ON(PageHighMem(pg)) triggers in
drivers/media/common/saa7146/saa7146_core.c since 19809c2da28a ("mm,
vmalloc: use __GFP_HIGHMEM implicitly").

saa7146_vmalloc_build_pgtable uses vmalloc_32 and it is reasonable to
expect that the resulting page is not in highmem.  The above commit
aimed to add __GFP_HIGHMEM only for those requests which do not specify
any zone modifier gfp flag.  vmalloc_32 relies on GFP_VMALLOC32 which
should do the right thing.  Except it has been missed that GFP_VMALLOC32
is an alias for GFP_KERNEL on 32b architectures.  Thanks to Matthew to
notice this.

Fix the problem by unconditionally setting GFP_DMA32 in GFP_VMALLOC32
for !64b arches (as a bailout).  This should do the right thing and use
ZONE_NORMAL which should be always below 4G on 32b systems.

Debugged by Matthew Wilcox.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20180212095019.GX21609@dhcp22.suse.cz
Fixes: 19809c2da28a ("mm, vmalloc: use __GFP_HIGHMEM implicitly”)
Signed-off-by: Michal Hocko 
Reported-by: Kai Heng Feng 
Cc: Matthew Wilcox 
Cc: Laura Abbott 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "vmalloc: back off when the current task is killed"

2017-10-13T23:18:32+00:00

This reverts commits 5d17a73a2ebe ("vmalloc: back off when the current
task is killed") and 171012f56127 ("mm: don't warn when vmalloc() fails
due to a fatal signal").

Commit 5d17a73a2ebe ("vmalloc: back off when the current task is
killed") made all vmalloc allocations from a signal-killed task fail.
We have seen crashes in the tty driver from this, where a killed task
exiting tries to switch back to N_TTY, fails n_tty_open because of the
vmalloc failing, and later crashes when dereferencing tty->disc_data.

Arguably, relying on a vmalloc() call to succeed in order to properly
exit a task is not the most robust way of doing things.  There will be a
follow-up patch to the tty code to fall back to the N_NULL ldisc.

But the justification to make that vmalloc() call fail like this isn't
convincing, either.  The patch mentions an OOM victim exhausting the
memory reserves and thus deadlocking the machine.  But the OOM killer is
only one, improbable source of fatal signals.  It doesn't make sense to
fail allocations preemptively with plenty of memory in most cases.

The patch doesn't mention real-life instances where vmalloc sites would
exhaust memory, which makes it sound more like a theoretical issue to
begin with.  But just in case, the OOM access to memory reserves has
been restricted on the allocator side in cd04ae1e2dc8 ("mm, oom: do not
rely on TIF_MEMDIE for memory reserves access"), which should take care
of any theoretical concerns on that front.

Revert this patch, and the follow-up that suppresses the allocation
warnings when we fail the allocations due to a signal.

Link: http://lkml.kernel.org/r/20171004185906.GB2136@cmpxchg.org
Fixes:  171012f56127 ("mm: don't warn when vmalloc() fails due to a fatal signal")
Signed-off-by: Johannes Weiner 
Acked-by: Vlastimil Babka 
Acked-by: Michal Hocko 
Cc: Alan Cox 
Cc: Christoph Hellwig 
Cc: Dmitry Vyukov 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds