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| author | Dmitry Safonov <dima@arista.com> | 2020-12-14 19:08:25 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-15 12:13:41 -0800 |
| commit | 871402e05b24cb56bc69df47cff960d0e0d24267 (patch) | |
| tree | f8235ea5b089ed3c9def2e9c6ed2df51d205e8d3 /mm/mmap.c | |
| parent | 73d5e06299195f4df82832cfc4a3a0c574c1e473 (diff) | |
| download | lwn-871402e05b24cb56bc69df47cff960d0e0d24267.tar.gz lwn-871402e05b24cb56bc69df47cff960d0e0d24267.zip | |
mm: forbid splitting special mappings
Don't allow splitting of vm_special_mapping's. It affects vdso/vvar
areas. Uprobes have only one page in xol_area so they aren't affected.
Those restrictions were enforced by checks in .mremap() callbacks.
Restrict resizing with generic .split() callback.
Link: https://lkml.kernel.org/r/20201013013416.390574-7-dima@arista.com
Signed-off-by: Dmitry Safonov <dima@arista.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 886de799e7d2..10598e5d4757 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3422,6 +3422,17 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma, return 0; } +static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) +{ + /* + * Forbid splitting special mappings - kernel has expectations over + * the number of pages in mapping. Together with VM_DONTEXPAND + * the size of vma should stay the same over the special mapping's + * lifetime. + */ + return -EINVAL; +} + static const struct vm_operations_struct special_mapping_vmops = { .close = special_mapping_close, .fault = special_mapping_fault, @@ -3429,6 +3440,7 @@ static const struct vm_operations_struct special_mapping_vmops = { .name = special_mapping_name, /* vDSO code relies that VVAR can't be accessed remotely */ .access = NULL, + .may_split = special_mapping_split, }; static const struct vm_operations_struct legacy_special_mapping_vmops = { |