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    SubjectRe: [PATCH] Fix user data corrupted by old value return of sysctl

    In article <> (at Fri, 30 Dec 2005 09:25:35 -0800 (PST)), Linus Torvalds <> says:

    > On Fri, 30 Dec 2005, Yi Yang wrote:
    > >
    > > If the user reads a sysctl entry which is of string type
    > > by sysctl syscall, this call probably corrupts the user data
    > > right after the old value buffer, the issue lies in sysctl_string
    > > seting 0 to oldval[len], len is the available buffer size
    > > specified by the user, obviously, this will write to the first
    > > byte of the user memory place immediate after the old value buffer,
    > > the correct way is that sysctl_string doesn't set 0, the user
    > > should do it by self in the program.
    > We _should_ zero-pad the data, at least if the result fits in the buffer.
    > But even that is questionable: one alternative is to always zero-pad (like
    > we used to), but make sure that the buffer size is sufficient for it (ie
    > instead of adding one to the length of the string, we'd subtract one from
    > the buffer length and make sure that the '\0' fits..

    How about returning -ENOMEM, as BSDs (FreeBSD and NetBSD
    at least) do. No?

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      Last update: 2005-12-31 12:49    [W:0.026 / U:0.044 seconds]
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