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    SubjectRe: [PATCH] fs/befs/linuxvfs.c: need signed cast for variable 'block'
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    On Thu, Oct 31, 2013 at 12:06 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
    > On Thu, Oct 31, 2013 at 09:53:59AM -0700, Kees Cook wrote:
    >
    >> If block (type sector_t) is unsigned, we shouldn't cast it signed.
    >> This entire code path should be removed. What is BEFS's expected
    >> maximum block size? (Looks like even befs_blocknr_t is u64, so nothing
    >> seems trivially in danger of wrapping.) I would also note that all the
    >> format strings are wrong too (%ld instead of %lu).
    >
    > FWIW, this
    > res = befs_fblock2brun(sb, ds, block, &run);
    > if (res != BEFS_OK) {
    > befs_error(sb,
    > "<--- befs_get_block() for inode %lu, block "
    > "%ld ERROR", inode->i_ino, block);
    > return -EFBIG;
    > }
    > also looks wrong - ioctl(..., FIBMAP, ...) shouldn't be able to spew
    > printks on a valid fs and hitting it with block number greater than
    > file length will, AFAICS, trigger that.
    >
    > I agree that this code needs fixing, but just making gcc STFU about the
    > comparison would only serve to hide the problem. Anybody familiar with
    > befs or willing to learn it?

    Agreed. MAINTAINERS shows it as orphaned. Perhaps it should be moved
    into staging?

    -Kees

    --
    Kees Cook
    Chrome OS Security


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