Hi Andy, Sorry for the late reply. On Wed, 13 Jan 2016 14:28:18 -0800, Andy Lutomirski wrote: > [cc: Jean Delvare] > > On Tue, Jan 12, 2016 at 6:25 AM, Pali Rohár <pali.rohar@xxxxxxxxx> wrote: > > On Monday 11 January 2016 13:58:20 Andy Lutomirski wrote: > >> On Sun, Jan 3, 2016 at 6:52 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: > >> > The dmi_walk function maps the DMI table, walks it, and unmaps it. > >> > This means that the dell_bios_hotkey_table that find_hk_type stores > >> > points to unmapped memory by the time it gets read. > >> > > >> > I've been able to trigger crashes caused by the stale pointer a > >> > couple of times, but never on a stock kernel. > >> > > >> > Fix it by generating the keymap in the dmi_walk callback instead of > >> > storing a pointer. > >> > >> Quick ping: has anyone had a chance to look at this? > > > > Hi Andy, I looked at this patch, but I think some people from -mm or DMI > > code should look at it as it is memory problem... We also has one in > > dell-laptop.ko (wrong API usage) and so -mm people could know it better. > > Let's ask: > > Jean, am I right that drivers must not store pointers to DMI tables > that they find through dmi_walk? Yes, you are right. > Is there any alternative interface > that could be used to get a longer-lived pointer to DMI tables, or > should drivers just parse them and copy out any info needed from the > dmi_walk callback? There is no alternative for OEM type records. Drivers are indeed expected to copy the information they need to their own buffers. > There are at least two platform drivers (dell-wmi and dell-laptop) > that don't play well with the current interface. This patch is > intended to fix one of them. Couldn't see any problem with dell-laptop. -- Jean Delvare SUSE L3 Support -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
