From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
Alexander Egorenkov <egorenar@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.14 02/50] mm/userfaultfd: do not access vma->vm_mm after calling handle_userfault()
Date: Tue, 1 Dec 2020 09:53:01 +0100 [thread overview]
Message-ID: <20201201084645.054722406@linuxfoundation.org> (raw)
In-Reply-To: <20201201084644.803812112@linuxfoundation.org>
From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
commit bfe8cc1db02ab243c62780f17fc57f65bde0afe1 upstream.
Alexander reported a syzkaller / KASAN finding on s390, see below for
complete output.
In do_huge_pmd_anonymous_page(), the pre-allocated pagetable will be
freed in some cases. In the case of userfaultfd_missing(), this will
happen after calling handle_userfault(), which might have released the
mmap_lock. Therefore, the following pte_free(vma->vm_mm, pgtable) will
access an unstable vma->vm_mm, which could have been freed or re-used
already.
For all architectures other than s390 this will go w/o any negative
impact, because pte_free() simply frees the page and ignores the
passed-in mm. The implementation for SPARC32 would also access
mm->page_table_lock for pte_free(), but there is no THP support in
SPARC32, so the buggy code path will not be used there.
For s390, the mm->context.pgtable_list is being used to maintain the 2K
pagetable fragments, and operating on an already freed or even re-used
mm could result in various more or less subtle bugs due to list /
pagetable corruption.
Fix this by calling pte_free() before handle_userfault(), similar to how
it is already done in __do_huge_pmd_anonymous_page() for the WRITE /
non-huge_zero_page case.
Commit 6b251fc96cf2c ("userfaultfd: call handle_userfault() for
userfaultfd_missing() faults") actually introduced both, the
do_huge_pmd_anonymous_page() and also __do_huge_pmd_anonymous_page()
changes wrt to calling handle_userfault(), but only in the latter case
it put the pte_free() before calling handle_userfault().
BUG: KASAN: use-after-free in do_huge_pmd_anonymous_page+0xcda/0xd90 mm/huge_memory.c:744
Read of size 8 at addr 00000000962d6988 by task syz-executor.0/9334
CPU: 1 PID: 9334 Comm: syz-executor.0 Not tainted 5.10.0-rc1-syzkaller-07083-g4c9720875573 #0
Hardware name: IBM 3906 M04 701 (KVM/Linux)
Call Trace:
do_huge_pmd_anonymous_page+0xcda/0xd90 mm/huge_memory.c:744
create_huge_pmd mm/memory.c:4256 [inline]
__handle_mm_fault+0xe6e/0x1068 mm/memory.c:4480
handle_mm_fault+0x288/0x748 mm/memory.c:4607
do_exception+0x394/0xae0 arch/s390/mm/fault.c:479
do_dat_exception+0x34/0x80 arch/s390/mm/fault.c:567
pgm_check_handler+0x1da/0x22c arch/s390/kernel/entry.S:706
copy_from_user_mvcos arch/s390/lib/uaccess.c:111 [inline]
raw_copy_from_user+0x3a/0x88 arch/s390/lib/uaccess.c:174
_copy_from_user+0x48/0xa8 lib/usercopy.c:16
copy_from_user include/linux/uaccess.h:192 [inline]
__do_sys_sigaltstack kernel/signal.c:4064 [inline]
__s390x_sys_sigaltstack+0xc8/0x240 kernel/signal.c:4060
system_call+0xe0/0x28c arch/s390/kernel/entry.S:415
Allocated by task 9334:
slab_alloc_node mm/slub.c:2891 [inline]
slab_alloc mm/slub.c:2899 [inline]
kmem_cache_alloc+0x118/0x348 mm/slub.c:2904
vm_area_dup+0x9c/0x2b8 kernel/fork.c:356
__split_vma+0xba/0x560 mm/mmap.c:2742
split_vma+0xca/0x108 mm/mmap.c:2800
mlock_fixup+0x4ae/0x600 mm/mlock.c:550
apply_vma_lock_flags+0x2c6/0x398 mm/mlock.c:619
do_mlock+0x1aa/0x718 mm/mlock.c:711
__do_sys_mlock2 mm/mlock.c:738 [inline]
__s390x_sys_mlock2+0x86/0xa8 mm/mlock.c:728
system_call+0xe0/0x28c arch/s390/kernel/entry.S:415
Freed by task 9333:
slab_free mm/slub.c:3142 [inline]
kmem_cache_free+0x7c/0x4b8 mm/slub.c:3158
__vma_adjust+0x7b2/0x2508 mm/mmap.c:960
vma_merge+0x87e/0xce0 mm/mmap.c:1209
userfaultfd_release+0x412/0x6b8 fs/userfaultfd.c:868
__fput+0x22c/0x7a8 fs/file_table.c:281
task_work_run+0x200/0x320 kernel/task_work.c:151
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
do_notify_resume+0x100/0x148 arch/s390/kernel/signal.c:538
system_call+0xe6/0x28c arch/s390/kernel/entry.S:416
The buggy address belongs to the object at 00000000962d6948 which belongs to the cache vm_area_struct of size 200
The buggy address is located 64 bytes inside of 200-byte region [00000000962d6948, 00000000962d6a10)
The buggy address belongs to the page: page:00000000313a09fe refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x962d6 flags: 0x3ffff00000000200(slab)
raw: 3ffff00000000200 000040000257e080 0000000c0000000c 000000008020ba00
raw: 0000000000000000 000f001e00000000 ffffffff00000001 0000000096959501
page dumped because: kasan: bad access detected
page->mem_cgroup:0000000096959501
Memory state around the buggy address:
00000000962d6880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000000962d6900: 00 fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb
>00000000962d6980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
00000000962d6a00: fb fb fc fc fc fc fc fc fc fc 00 00 00 00 00 00
00000000962d6a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Changes for v4.14 stable:
- Make it apply w/o
* Commit 4cf58924951ef ("mm: treewide: remove unused address argument
from pte_alloc functions")
* Commit 2b7403035459c ("mm: Change return type int to vm_fault_t for
fault handlers")
Fixes: 6b251fc96cf2c ("userfaultfd: call handle_userfault() for userfaultfd_missing() faults")
Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: <stable@vger.kernel.org> [4.3+]
Link: https://lkml.kernel.org/r/20201110190329.11920-1-gerald.schaefer@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -688,7 +688,6 @@ int do_huge_pmd_anonymous_page(struct vm
transparent_hugepage_use_zero_page()) {
pgtable_t pgtable;
struct page *zero_page;
- bool set;
int ret;
pgtable = pte_alloc_one(vma->vm_mm, haddr);
if (unlikely(!pgtable))
@@ -701,25 +700,25 @@ int do_huge_pmd_anonymous_page(struct vm
}
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
ret = 0;
- set = false;
if (pmd_none(*vmf->pmd)) {
ret = check_stable_address_space(vma->vm_mm);
if (ret) {
spin_unlock(vmf->ptl);
+ pte_free(vma->vm_mm, pgtable);
} else if (userfaultfd_missing(vma)) {
spin_unlock(vmf->ptl);
+ pte_free(vma->vm_mm, pgtable);
ret = handle_userfault(vmf, VM_UFFD_MISSING);
VM_BUG_ON(ret & VM_FAULT_FALLBACK);
} else {
set_huge_zero_page(pgtable, vma->vm_mm, vma,
haddr, vmf->pmd, zero_page);
spin_unlock(vmf->ptl);
- set = true;
}
- } else
+ } else {
spin_unlock(vmf->ptl);
- if (!set)
pte_free(vma->vm_mm, pgtable);
+ }
return ret;
}
gfp = alloc_hugepage_direct_gfpmask(vma);
next prev parent reply other threads:[~2020-12-01 9:30 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 8:52 [PATCH 4.14 00/50] 4.14.210-rc1 review Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 01/50] perf event: Check ref_reloc_sym before using it Greg Kroah-Hartman
2020-12-01 8:53 ` Greg Kroah-Hartman [this message]
2020-12-01 8:53 ` [PATCH 4.14 03/50] btrfs: fix lockdep splat when reading qgroup config on mount Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 04/50] wireless: Use linux/stddef.h instead of stddef.h Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 05/50] PCI: Add device even if driver attach failed Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 06/50] btrfs: tree-checker: Enhance chunk checker to validate chunk profile Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 07/50] btrfs: adjust return values of btrfs_inode_by_name Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 08/50] btrfs: inode: Verify inode mode to avoid NULL pointer dereference Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 09/50] KVM: x86: Fix split-irqchip vs interrupt injection window request Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 10/50] arm64: pgtable: Fix pte_accessible() Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 11/50] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 12/50] ALSA: hda/hdmi: Use single mutex unlock in error paths Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 13/50] ALSA: hda/hdmi: fix incorrect locking in hdmi_pcm_close Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 14/50] HID: cypress: Support Varmilo Keyboards media hotkeys Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 15/50] Input: i8042 - allow insmod to succeed on devices without an i8042 controller Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 16/50] HID: hid-sensor-hub: Fix issue with devices with no report ID Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 17/50] dmaengine: xilinx_dma: use readl_poll_timeout_atomic variant Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 18/50] x86/xen: dont unbind uninitialized lock_kicker_irq Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 19/50] HID: Add Logitech Dinovo Edge battery quirk Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 20/50] proc: dont allow async path resolution of /proc/self components Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 21/50] nvme: free sq/cq dbbuf pointers when dbbuf set fails Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 22/50] dmaengine: pl330: _prep_dma_memcpy: Fix wrong burst size Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 23/50] scsi: libiscsi: Fix NOP race condition Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 24/50] scsi: target: iscsi: Fix cmd abort fabric stop race Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 25/50] perf/x86: fix sysfs type mismatches Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 26/50] phy: tegra: xusb: Fix dangling pointer on probe failure Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 27/50] batman-adv: set .owner to THIS_MODULE Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 28/50] scsi: ufs: Fix race between shutdown and runtime resume flow Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 29/50] bnxt_en: fix error return code in bnxt_init_one() Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 30/50] bnxt_en: fix error return code in bnxt_init_board() Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 31/50] video: hyperv_fb: Fix the cache type when mapping the VRAM Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 32/50] bnxt_en: Release PCI regions when DMA mask setup fails during probe Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 33/50] IB/mthca: fix return value of error branch in mthca_init_cq() Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 34/50] nfc: s3fwrn5: use signed integer for parsing GPIO numbers Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 35/50] net: ena: set initial DMA width to avoid intel iommu issue Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 36/50] ibmvnic: fix NULL pointer dereference in reset_sub_crq_queues Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 37/50] ibmvnic: fix NULL pointer dereference in ibmvic_reset_crq Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 38/50] efivarfs: revert "fix memory leak in efivarfs_create()" Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 39/50] can: gs_usb: fix endianess problem with candleLight firmware Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 40/50] platform/x86: toshiba_acpi: Fix the wrong variable assignment Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 41/50] can: m_can: fix nominal bitiming tseg2 min for version >= 3.1 Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 42/50] perf probe: Fix to die_entrypc() returns error correctly Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 43/50] USB: core: Change %pK for __user pointers to %px Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 44/50] usb: gadget: f_midi: Fix memleak in f_midi_alloc Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 45/50] usb: gadget: Fix memleak in gadgetfs_fill_super Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 46/50] x86/speculation: Fix prctl() when spectre_v2_user={seccomp,prctl},ibpb Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 47/50] x86/resctrl: Remove superfluous kernfs_get() calls to prevent refcount leak Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 48/50] x86/resctrl: Add necessary kernfs_put() " Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 49/50] USB: core: add endpoint-blacklist quirk Greg Kroah-Hartman
2020-12-01 8:53 ` [PATCH 4.14 50/50] USB: core: Fix regression in Hercules audio card Greg Kroah-Hartman
2020-12-01 21:39 ` [PATCH 4.14 00/50] 4.14.210-rc1 review Guenter Roeck
2020-12-02 6:04 ` Naresh Kamboju
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