Re: [patch] groups: integer underflow in groups_alloc()

From: Dan Carpenter
Date: Mon Feb 23 2015 - 13:03:53 EST

On Mon, Feb 23, 2015 at 11:10:02AM -0600, Eric W. Biederman wrote:
> Dan Carpenter <dan.carpenter@xxxxxxxxxx> writes:
> > This is called from rsc_parse() with a use controlled value. Say for
> > example that "gidsetsize" is negative, then we could end up allocating
> > less than sizeof(struct group_info) leading to memory corruption.
> Right now it is the responsibility of the caller of groups_alloc to make
> certain that gidsetsize is a valid value, and the callers of
> groups_alloc who know what they are doing already validate this value.
> Either the pattern of caller validates the messages needs to continue,
> or groups_alloc needs to be changed and all of the callers need to be
> updated.
> Changing groups_alloc for one particular caller is just going to cause
> maintenance problems.

This only affects NFS so let's hear from them if this limit is correct
and decide from there.

dan carpenter

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