Hi Jiri, Some notes regarding picoLCD part below.
On Tue, 09 July 2013 Jiri Kosina <[email protected]> wrote: > implement() is setting bytes in LE data stream. In case the data > is not aligned to 64bits, it reads past the allocated buffer. It > doesn't really change any value there (it's properly bitmasked), but > in case that this read past the boundary hits a page boundary, pagefault > happens when accessing 64bits of 'x' in implement(), and kernel oopses. > > This happens much more often when numbered reports are in use, as the > initial 8bit skip in the buffer makes the whole process work on values > which are not aligned to 64bits. > > This problem dates back to attempts in 2005 and 2006 to make implement() > and extract() as generic as possible, and even back then the problem > was realized by Adam Kroperlin, but falsely assumed to be impossible > to cause any harm: > > > http://www.mail-archive.com/[email protected]/msg47690.html > > I have made several attempts at fixing it "on the spot" directly in > implement(), but the results were horrible; the special casing for processing > last 64bit chunk and switching to different math makes it unreadable mess. > > I therefore took a path to allocate a few bytes more which will never make > it into final report, but are there as a cushion for all the 64bit math > operations happening in implement() and extract(). > > All callers of hid_output_report() are converted at the same time to allocate > the buffer by newly introduced hid_alloc_report_buf() helper. > > Signed-off-by: Jiri Kosina <[email protected]> > --- > drivers/hid/hid-core.c | 19 ++++++++++++++++++- > drivers/hid/hid-logitech-dj.c | 12 ++++++++++-- > drivers/hid/hid-picolcd_debugfs.c | 10 +++++++++- > drivers/hid/usbhid/hid-core.c | 4 ++-- > include/linux/hid.h | 1 + > net/bluetooth/hidp/core.c | 14 +++++++++----- > 6 files changed, 49 insertions(+), 11 deletions(-) > > diff --git a/drivers/hid/hid-picolcd_debugfs.c > b/drivers/hid/hid-picolcd_debugfs.c > index 59ab8e1..784a17c 100644 > --- a/drivers/hid/hid-picolcd_debugfs.c > +++ b/drivers/hid/hid-picolcd_debugfs.c > @@ -394,7 +394,7 @@ static void dump_buff_as_hex(char *dst, size_t dst_sz, > const u8 *data, > void picolcd_debug_out_report(struct picolcd_data *data, > struct hid_device *hdev, struct hid_report *report) > { > - u8 raw_data[70]; > + u8 *raw_data; > int raw_size = (report->size >> 3) + 1; > char *buff; > #define BUFF_SZ 256 > @@ -407,11 +407,18 @@ void picolcd_debug_out_report(struct picolcd_data *data, > if (!buff) > return; > > + raw_data = hid_alloc_report_buf(report, GFP_ATOMIC); > + if (!raw_data) { > + kfree(buff); > + return; > + } > + > snprintf(buff, BUFF_SZ, "\nout report %d (size %d) = ", > report->id, raw_size); > hid_debug_event(hdev, buff); > if (raw_size + 5 > sizeof(raw_data)) { As you change raw_data from u8[] to u8* the sizeof(raw_data) will not do the right thing. In addition the whole test (if it were correct) is not needed anymore as hid_alloc_report_buf() should always return a buffer of sufficient size. So just drop the test: - if (raw_size + 5 > sizeof(raw_data)) { - kfree(buff); - hid_debug_event(hdev, " TOO BIG\n"); - return; - } else { - raw_data[0] = report->id; - hid_output_report(report, raw_data); - dump_buff_as_hex(buff, BUFF_SZ, raw_data, raw_size); - hid_debug_event(hdev, buff); - } + raw_data[0] = report->id; + hid_output_report(report, raw_data); + dump_buff_as_hex(buff, BUFF_SZ, raw_data, raw_size); + hid_debug_event(hdev, buff); > kfree(buff); > + kfree(raw_data); > hid_debug_event(hdev, " TOO BIG\n"); > return; > } else { > @@ -644,6 +651,7 @@ void picolcd_debug_out_report(struct picolcd_data *data, > break; > } > wake_up_interruptible(&hdev->debug_wait); > + kfree(raw_data); > kfree(buff); > } > Bruno -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
