diff options
| author | Julius Werner <jwerner@chromium.org> | 2017-05-12 14:42:58 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-25 14:30:18 +0200 |
| commit | 837bfdb41337fc6b82dbde4b2ec3ce923845049f (patch) | |
| tree | 88efa00280687d6da5bb13f0d19e5e0cf54c8208 | |
| parent | 52cf24769487de7100d824e8c12ecc310de841d7 (diff) | |
drivers: char: mem: Check for address space wraparound with mmap()
commit b299cde245b0b76c977f4291162cf668e087b408 upstream.
/dev/mem currently allows mmap() mappings that wrap around the end of
the physical address space, which should probably be illegal. It
circumvents the existing STRICT_DEVMEM permission check because the loop
immediately terminates (as the start address is already higher than the
end address). On the x86_64 architecture it will then cause a panic
(from the BUG(start >= end) in arch/x86/mm/pat.c:reserve_memtype()).
This patch adds an explicit check to make sure offset + size will not
wrap around in the physical address type.
Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/char/mem.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c index e901463d4972..0975d23031ea 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -343,6 +343,11 @@ static const struct vm_operations_struct mmap_mem_ops = { static int mmap_mem(struct file *file, struct vm_area_struct *vma) { size_t size = vma->vm_end - vma->vm_start; + phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; + + /* It's illegal to wrap around the end of the physical address space. */ + if (offset + (phys_addr_t)size < offset) + return -EINVAL; if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) return -EINVAL; |