Messages in this thread | | | Date | Tue, 2 Feb 2021 22:51:01 +0300 | From | Dan Carpenter <> | Subject | Re: [PATCH 4.4 24/28] can: dev: prevent potential information leak in can_fill_info() |
| |
On Tue, Feb 02, 2021 at 10:05:39PM +0300, Dan Carpenter wrote: > On Tue, Feb 02, 2021 at 07:53:17PM +0100, Pavel Machek wrote: > > Hi! > > > > > From: Dan Carpenter <dan.carpenter@oracle.com> > > > > > > [ Upstream commit b552766c872f5b0d90323b24e4c9e8fa67486dd5 ] > > > > > > The "bec" struct isn't necessarily always initialized. For example, the > > > mcp251xfd_get_berr_counter() function doesn't initialize anything if the > > > interface is down. > > > > Well, yes... and = {} does not neccessarily initialize all of the > > structure... for example padding. > > > > It is really simple > > > > struct can_berr_counter { > > __u16 txerr; > > __u16 rxerr; > > }; > > > > but maybe something like alpha uses padding in such case, and memset > > would be better? > > I'm pretty sure nothing uses padding in this situation. If it does then > we need to re-work a bunch of code.
Not necessarily related but in theory a "= {};" assignment is a GCC extension and it is supposed to zero out struct holes. If the code does "= {0};" then that's standard C, and will not necessarily fill struct holes but I think GCC tries to. The other complication is that some GCC versions have bugs related to this? We had a long thread about this last August.
https://lore.kernel.org/lkml/20200801144030.GM24045@ziepe.ca/
Anyway, this code has no holes so it's not affected.
regards, dan carpenter
| |