Messages in this thread |  | | | Date | Tue, 23 Feb 2010 23:45:19 +0800 | | From | Américo Wang <> | | Subject | Re: [RESEND PATCH] module param_call: fix potential NULL pointer dereference |
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On Tue, Feb 23, 2010 at 02:26:45PM +1030, Rusty Russell wrote: >On Mon, 22 Feb 2010 09:10:51 pm Dongdong Deng wrote: >> The param_set_fn() function will get a parameter which is a NULL >> pointer when insmod module via bare params as following method: >> >> $insmod foo.ko foo >> >> If the param_set_fn() function didn't check that parameter and used >> it directly, it could caused an OOPS due to NULL pointer dereference. >> >> The solution is simple: >> Using "" to replace NULL parameter, thereby the param_set_fn() >> function will never get a NULL pointer. > >This changes the value of booleans, and loses checking for int params, etc. > >I liked Americo's approach; I've combined the two approaches below. > >Since I'm going away, can Andrew take this? > >Subject: params: don't hand NULL values to param.set callbacks. > >An audit by Dongdong Deng revealed that most driver-author-written param >calls don't handle val == NULL (which happens when parameters are specified >with no =, eg "foo" instead of "foo=1"). > >The only real case to use this is boolean, so handle it specially for that >case and remove a source of bugs for everyone else as suggested by Americo. > >Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> >Cc: Dongdong Deng <dongdong.deng@windriver.com> >Cc: Américo Wang <xiyou.wangcong@gmail.com> > >diff --git a/kernel/params.c b/kernel/params.c >--- a/kernel/params.c >+++ b/kernel/params.c >@@ -59,6 +59,9 @@ static int parse_one(char *param, > /* Find parameter */ > for (i = 0; i < num_params; i++) { > if (parameq(param, params[i].name)) { >+ /* Noone handled NULL, so do it here. */ >+ if (!val && params[i].set != param_set_bool) >+ return -EINVAL;
Sorry, after rethinking about this, I think it might be wrong.
With this patch, when I use non-standard bool functions, I will not have a chance to use '!val' which should be valid for all bool functions. Or am I missing something?
Thanks.
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