Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.18 37/45] drivers: char: mem: Fix wraparound check to allow mappings up to the end | Date | Mon, 12 Jun 2017 17:26:47 +0200 |
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3.18-stable review patch. If anyone has any objections, please let me know.
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From: Julius Werner <jwerner@chromium.org>
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>
--- drivers/char/mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -332,7 +332,7 @@ static int mmap_mem(struct file *file, s 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))
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