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udf: fix udf_build_ustr

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udf_build_ustr was broken:

- size == 1:
    dest->u_len = ptr[1 - 1], but at ptr[0] there's cmpID,
    so we created string with wrong length
    it should not happen, so we BUG() it
- size > 1 and size < UDF_NAME_LEN:
    we set u_len correctly, but memcpy copied one needless byte
- size == UDF_NAME_LEN - 1:
    memcpy overwrited u_len - with correct value, but...
- size >= UDF_NAME_LEN:
    we copied UDF_NAME_LEN - 1 bytes, but dest->u_name is array
    of UDF_NAME_LEN - 2 bytes, so we were overwriting u_len with
    character from input string

nobody noticed because all callers set size
to acceptable values (constants within range)

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Marcin Slusarz 2008-02-04 22:27:39 +01:00 committed by Jan Kara
parent 79cfe0ff5f
commit 6305a0a9d5
1 changed files with 7 additions and 5 deletions
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12
fs/udf/unicode.c
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@ -48,14 +48,16 @@ int udf_build_ustr(struct ustr *dest, dstring *ptr, int size)
{
int usesize;
if ((!dest) || (!ptr) || (!size))
if (!dest || !ptr || !size)
return -1;
BUG_ON(size < 2);
memset(dest, 0, sizeof(struct ustr));
usesize = (size > UDF_NAME_LEN) ? UDF_NAME_LEN : size;
usesize = min_t(size_t, ptr[size - 1], sizeof(dest->u_name));
usesize = min(usesize, size - 2);
dest->u_cmpID = ptr[0];
dest->u_len = ptr[size - 1];
memcpy(dest->u_name, ptr + 1, usesize - 1);
dest->u_len = usesize;
memcpy(dest->u_name, ptr + 1, usesize);
memset(dest->u_name + usesize, 0, sizeof(dest->u_name) - usesize);
return 0;
}