On Fri, Apr 22, 2016 at 09:32:17AM +0200, [email protected] wrote:
> coda-src/vtools/cfs.cc | 27 +++++++++++++++++++--------
> 1 files changed, 19 insertions(+), 8 deletions(-)
>
> --- a/coda-src/vtools/cfs.cc
> +++ b/coda-src/vtools/cfs.cc
> @@ -1826,8 +1826,8 @@ static void ListVolume(int argc, char *argv[], int
> opslot)
> VolumeStatus *vs;
> char *volname, *omsg, *motd;
> VolumeStateType conn_state;
> - int conflict, cml_count;
> - unsigned int age, time;
> + int32_t conflict, cml_count;
> + uint32_t age, time;
> uint64_t cml_bytes;
> char *ptr;
> int local_only = 0;
> @@ -1859,25 +1859,36 @@ static void ListVolume(int argc, char *argv[], int
> opslot)
> cml_count, offlinemsg, motd, age, time, cml_bytes) */
> ptr = piobuf; /* invariant: ptr always point to next obj
> to be read */
> +/* we hope that piobuf is sufficiently well aligned */
It should because as far as I remember to make it easier on the kernel
it is always aligned on a page boundary and always smaller than the size
of a memory page.
> vs = (VolumeStatus *)ptr;
> ptr += sizeof(VolumeStatus);
> volname = ptr; ptr += strlen(volname)+1;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Here is the real culprit, if those strings were padded to the next
32-bit boundary none of the rest would even be necessary.
> - conn_state = (VolumeStateType)*(int32_t *)ptr;
> +/* avoid unaligned memory accesses */
> + { int32_t temp;
> + memcpy(&temp, ptr, sizeof(int32_t));
> + conn_state = (VolumeStateType)temp;
> + }
> +/* conn_state = (VolumeStateType)*(int32_t *)ptr; */
I am somewhat surprised you aren't getting the same alignment errors
when this is packed on the venus side, because the code there is pretty
much identical and even has a comment about possible alignment issues.
/* do we have to worry about alignment? */
*(int32_t *)cp = (int32_t)conn_state; cp += sizeof(int32_t);
...
This just needs to be fixed by padding the strings out.
I can't believe this was the only place that had an alignment problem
like this, those ioctls are badly packed all over the place.
Jan
