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    Subject[PATCH 4.14 117/211] fs/hfs/extent.c: fix array out of bounds read of array extent
    Date
    From: Colin Ian King <colin.king@canonical.com>

    [ Upstream commit 6c9a3f843a29d6894dfc40df338b91dbd78f0ae3 ]

    Currently extent and index i are both being incremented causing an array
    out of bounds read on extent[i]. Fix this by removing the extraneous
    increment of extent.

    Ernesto said:

    : This is only triggered when deleting a file with a resource fork. I
    : may be wrong because the documentation isn't clear, but I don't think
    : you can create those under linux. So I guess nobody was testing them.
    :
    : > A disk space leak, perhaps?
    :
    : That's what it looks like in general. hfs_free_extents() won't do
    : anything if the block count doesn't add up, and the error will be
    : ignored. Now, if the block count randomly does add up, we could see
    : some corruption.

    Detected by CoverityScan, CID#711541 ("Out of bounds read")

    Link: http://lkml.kernel.org/r/20180831140538.31566-1-colin.king@canonical.com
    Signed-off-by: Colin Ian King <colin.king@canonical.com>
    Reviewed-by: Ernesto A. Fernndez <ernesto.mnd.fernandez@gmail.com>
    Cc: David Howells <dhowells@redhat.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
    Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/hfs/extent.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/fs/hfs/extent.c b/fs/hfs/extent.c
    index 5f1ff97a3b987..263d5028d9d18 100644
    --- a/fs/hfs/extent.c
    +++ b/fs/hfs/extent.c
    @@ -304,7 +304,7 @@ int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type)
    return 0;

    blocks = 0;
    - for (i = 0; i < 3; extent++, i++)
    + for (i = 0; i < 3; i++)
    blocks += be16_to_cpu(extent[i].count);

    res = hfs_free_extents(sb, extent, blocks, blocks);
    --
    2.20.1


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