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    Subject[PATCH 5.4 144/191] uaccess: disallow > INT_MAX copy sizes
    Date
    From: Kees Cook <keescook@chromium.org>

    commit 6d13de1489b6bf539695f96d945de3860e6d5e17 upstream.

    As we've done with VFS, string operations, etc, reject usercopy sizes
    larger than INT_MAX, which would be nice to have for catching bugs
    related to size calculation overflows[1].

    This adds 10 bytes to x86_64 defconfig text and 1980 bytes to the data
    section:

    text data bss dec hex filename
    19691167 5134320 1646664 26472151 193eed7 vmlinux.before
    19691177 5136300 1646664 26474141 193f69d vmlinux.after

    [1] https://marc.info/?l=linux-s390&m=156631939010493&w=2

    Link: http://lkml.kernel.org/r/201908251612.F9902D7A@keescook
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    include/linux/thread_info.h | 2 ++
    1 file changed, 2 insertions(+)

    --- a/include/linux/thread_info.h
    +++ b/include/linux/thread_info.h
    @@ -147,6 +147,8 @@ check_copy_size(const void *addr, size_t
    __bad_copy_to();
    return false;
    }
    + if (WARN_ON_ONCE(bytes > INT_MAX))
    + return false;
    check_object_size(addr, bytes, is_source);
    return true;
    }

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