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authorDan Williams <dan.j.williams@intel.com>2017-11-29 16:10:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-29 18:40:42 -0800
commit9702cffdbf2129516db679e4467db81e1cd287da (patch)
tree24d44102dbff126e931c1a169d2fd495980b342c /drivers
parent31383c6865a578834dd953d9dbc88e6b19fe3997 (diff)
device-dax: implement ->split() to catch invalid munmap attempts
Similar to how device-dax enforces that the 'address', 'offset', and 'len' parameters to mmap() be aligned to the device's fundamental alignment, the same constraints apply to munmap(). Implement ->split() to fail munmap calls that violate the alignment constraint. Otherwise, we later fail VM_BUG_ON checks in the unmap_page_range() path with crash signatures of the form: vma ffff8800b60c8a88 start 00007f88c0000000 end 00007f88c0e00000 next (null) prev (null) mm ffff8800b61150c0 prot 8000000000000027 anon_vma (null) vm_ops ffffffffa0091240 pgoff 0 file ffff8800b638ef80 private_data (null) flags: 0x380000fb(read|write|shared|mayread|maywrite|mayexec|mayshare|softdirty|mixedmap|hugepage) ------------[ cut here ]------------ kernel BUG at mm/huge_memory.c:2014! [..] RIP: 0010:__split_huge_pud+0x12a/0x180 [..] Call Trace: unmap_page_range+0x245/0xa40 ? __vma_adjust+0x301/0x990 unmap_vmas+0x4c/0xa0 unmap_region+0xae/0x120 ? __vma_rb_erase+0x11a/0x230 do_munmap+0x276/0x410 vm_munmap+0x6a/0xa0 SyS_munmap+0x1d/0x30 Link: http://lkml.kernel.org/r/151130418681.4029.7118245855057952010.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Jeff Moyer <jmoyer@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/dax/device.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 6833ada237ab..7b0bf825c4e7 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -428,9 +428,21 @@ static int dev_dax_fault(struct vm_fault *vmf)
return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
}
+static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
+{
+ struct file *filp = vma->vm_file;
+ struct dev_dax *dev_dax = filp->private_data;
+ struct dax_region *dax_region = dev_dax->region;
+
+ if (!IS_ALIGNED(addr, dax_region->align))
+ return -EINVAL;
+ return 0;
+}
+
static const struct vm_operations_struct dax_vm_ops = {
.fault = dev_dax_fault,
.huge_fault = dev_dax_huge_fault,
+ .split = dev_dax_split,
};
static int dax_mmap(struct file *filp, struct vm_area_struct *vma)