Messages in this thread | | | Date | Thu, 16 Sep 2010 11:54:23 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v2] drivers/net/cxgb3/cxgb3_main.c: prevent reading uninitialized stack memory |
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On Wed, Sep 15, 2010 at 05:43:12PM -0400, Dan Rosenberg wrote: > Fixed formatting (tabs and line breaks). > > The CHELSIO_GET_QSET_NUM device ioctl allows unprivileged users to read > 4 bytes of uninitialized stack memory, because the "addr" member of the > ch_reg struct declared on the stack in cxgb_extension_ioctl() is not > altered or zeroed before being copied back to the user. This patch > takes care of it. > > Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com> > > --- linux-2.6.35.4.orig/drivers/net/cxgb3/cxgb3_main.c 2010-08-26 19:47:12.000000000 -0400 > +++ linux-2.6.35.4/drivers/net/cxgb3/cxgb3_main.c 2010-09-14 21:24:34.369511115 -0400 > @@ -2296,6 +2296,8 @@ static int cxgb_extension_ioctl(struct n > case CHELSIO_GET_QSET_NUM:{ > struct ch_reg edata; > > + memset(&edata, 0, sizeof(struct ch_reg)); > + > edata.cmd = CHELSIO_GET_QSET_NUM; > edata.val = pi->nqsets;
This is a pretty expensive way to fix it. either...
+ edata.addr = 0;
or:
- struct ch_reg edata; + struct ch_reg edata = { + .cmd = CHELSIO_GET_QSET_NUM, + .val = pi->nqsets + };
- edata.cmd = CHELSIO_GET_QSET_NUM; - edata.val = pi->nqsets;
If you are worried that the struct ch_reg may grow someday.
-- Steve
> if (copy_to_user(useraddr, &edata, sizeof(edata))) > >
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