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authorJulius Werner <jwerner@chromium.org>2017-06-02 15:36:39 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-14 15:06:04 +0200
commit9ff4a1a36a587b0343a02518dbc1d5bf4c0c99e8 (patch)
treedaeca9404c8e1bd545b49fc78d86095b0e8a574a
parent106c77e82572921fa53483235a55adb7cb9452c0 (diff)
drivers: char: mem: Fix wraparound check to allow mappings up to the end
commit 32829da54d9368103a2f03269a5120aa9ee4d5da upstream. A recent fix to /dev/mem prevents mappings from wrapping around the end of physical address space. However, the check was written in a way that also prevents a mapping reaching just up to the end of physical address space, which may be a valid use case (especially on 32-bit systems). This patch fixes it by checking the last mapped address (instead of the first address behind that) for overflow. Fixes: b299cde245 ("drivers: char: mem: Check for address space wraparound with mmap()") Reported-by: Nico Huber <nico.h@gmx.de> Signed-off-by: Julius Werner <jwerner@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/char/mem.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 6e0cbe092220..593a8818aca9 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -343,7 +343,7 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
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)
+ if (offset + (phys_addr_t)size - 1 < offset)
return -EINVAL;
if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))