tree 89099e1078b50ff770f06a86106edc72dc52563f
parent 1bc9fac3da9aa7569e70e9fda605281ef7e42b9f
author Petr Tesarik <ptesarik@suse.cz> 1391071682 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1392493862 -0800

/dev/mem: handle out-of-bounds read/write

The loff_t type may be wider than phys_addr_t (e.g. on 32-bit systems).
Consequently, the file offset may be truncated in the assignment.
Currently, /dev/mem wraps around, which may cause applications to read
or write incorrect regions of memory by accident.

Let's follow POSIX file semantics here and return 0 when reading from
and -EFBIG when writing to an offset that cannot be represented by a
phys_addr_t.

Note that the conditional is optimized out by the compiler if loff_t
has the same size as phys_addr_t.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>