| Message ID | 20200827113806.1850687-1-ppandit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fdc: check null block pointer before blk_pwrite | expand |
+-- On Thu, 27 Aug 2020, P J P wrote --+
| While transferring data via fdctrl_write_data(), check that
| current drive does not have a null block pointer. Avoid
| null pointer dereference.
|
| -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Ffdc_nullptr1
| ==1658854==Hint: address points to the zero page.
| #0 blk_inc_in_flight block/block-backend.c:1327
| #1 blk_prw block/block-backend.c:1299
| #2 blk_pwrite block/block-backend.c:1464
| #3 fdctrl_write_data hw/block/fdc.c:2418
| #4 fdctrl_write hw/block/fdc.c:962
| #5 portio_write ioport.c:205
| #6 memory_region_write_accessor memory.c:483
| #7 access_with_adjusted_size memory.c:544
| #8 memory_region_dispatch_write memory.c:1476
|
| Reported-by: Ruhr-University <bugs-syssec@rub.de>
| Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
| ---
| hw/block/fdc.c | 3 ++-
| 1 file changed, 2 insertions(+), 1 deletion(-)
|
| diff --git a/hw/block/fdc.c b/hw/block/fdc.c
| index e9ed3eef45..dedadac68a 100644
| --- a/hw/block/fdc.c
| +++ b/hw/block/fdc.c
| @@ -2419,7 +2419,8 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value)
| if (pos == FD_SECTOR_LEN - 1 ||
| fdctrl->data_pos == fdctrl->data_len) {
| cur_drv = get_cur_drv(fdctrl);
| - if (blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo,
| + if (cur_drv->blk
| + && blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo,
| BDRV_SECTOR_SIZE, 0) < 0) {
| FLOPPY_DPRINTF("error writing sector %d\n",
| fd_sector(cur_drv));
|
Ping...!
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
P J P <ppandit@redhat.com> 于2020年8月27日周四 下午7:41写道： > > From: Prasad J Pandit <pjp@fedoraproject.org> > > While transferring data via fdctrl_write_data(), check that > current drive does not have a null block pointer. Avoid > null pointer dereference. > > -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Ffdc_nullptr1 > ==1658854==Hint: address points to the zero page. > #0 blk_inc_in_flight block/block-backend.c:1327 > #1 blk_prw block/block-backend.c:1299 > #2 blk_pwrite block/block-backend.c:1464 > #3 fdctrl_write_data hw/block/fdc.c:2418 > #4 fdctrl_write hw/block/fdc.c:962 > #5 portio_write ioport.c:205 > #6 memory_region_write_accessor memory.c:483 > #7 access_with_adjusted_size memory.c:544 > #8 memory_region_dispatch_write memory.c:1476 > > Reported-by: Ruhr-University <bugs-syssec@rub.de> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/block/fdc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/block/fdc.c b/hw/block/fdc.c > index e9ed3eef45..dedadac68a 100644 > --- a/hw/block/fdc.c > +++ b/hw/block/fdc.c > @@ -2419,7 +2419,8 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value) > if (pos == FD_SECTOR_LEN - 1 || > fdctrl->data_pos == fdctrl->data_len) { > cur_drv = get_cur_drv(fdctrl); > - if (blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, > + if (cur_drv->blk > + && blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, > BDRV_SECTOR_SIZE, 0) < 0) { > FLOPPY_DPRINTF("error writing sector %d\n", > fd_sector(cur_drv)); > -- Hello Prasad, There are several pattern to address this NULL check in fdc.c. I think it is better to consider this as an error. Just like the check in 'fdctrl_format_sector': if (cur_drv->blk == NULL || blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, BDRV_SECTOR_SIZE, 0) < 0) { FLOPPY_DPRINTF("error formatting sector %d\n", fd_sector(cur_drv)); fdctrl_stop_transfer(fdctrl, FD_SR0_ABNTERM | FD_SR0_SEEK, 0x00, 0x00); } else { Also there seems exists the same issue in 'fdctrl_read_data' Thanks, Li Qiang > 2.26.2 > >
On 8/27/20 7:38 AM, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While transferring data via fdctrl_write_data(), check that > current drive does not have a null block pointer. Avoid > null pointer dereference. > Hi PJP. I assume this patch actually covers the exact same thing that the other if cur_drv->blk patch we have been discussing recently does. You may want to combine the Reported-By lines for both. I am dropping this patch from my queue in favor of pursuing our other, more recent and active thread, which I am also now tracking via this gitlab issue: https://gitlab.com/qemu-project/qemu/-/issues/338 > -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Ffdc_nullptr1 > ==1658854==Hint: address points to the zero page. > #0 blk_inc_in_flight block/block-backend.c:1327 > #1 blk_prw block/block-backend.c:1299 > #2 blk_pwrite block/block-backend.c:1464 > #3 fdctrl_write_data hw/block/fdc.c:2418 > #4 fdctrl_write hw/block/fdc.c:962 > #5 portio_write ioport.c:205 > #6 memory_region_write_accessor memory.c:483 > #7 access_with_adjusted_size memory.c:544 > #8 memory_region_dispatch_write memory.c:1476 > > Reported-by: Ruhr-University <bugs-syssec@rub.de> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/block/fdc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/block/fdc.c b/hw/block/fdc.c > index e9ed3eef45..dedadac68a 100644 > --- a/hw/block/fdc.c > +++ b/hw/block/fdc.c > @@ -2419,7 +2419,8 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value) > if (pos == FD_SECTOR_LEN - 1 || > fdctrl->data_pos == fdctrl->data_len) { > cur_drv = get_cur_drv(fdctrl); > - if (blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, > + if (cur_drv->blk > + && blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, > BDRV_SECTOR_SIZE, 0) < 0) { > FLOPPY_DPRINTF("error writing sector %d\n", > fd_sector(cur_drv)); >
diff --git a/hw/block/fdc.c b/hw/block/fdc.c index e9ed3eef45..dedadac68a 100644 --- a/hw/block/fdc.c +++ b/hw/block/fdc.c @@ -2419,7 +2419,8 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value) if (pos == FD_SECTOR_LEN - 1 || fdctrl->data_pos == fdctrl->data_len) { cur_drv = get_cur_drv(fdctrl); - if (blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, + if (cur_drv->blk + && blk_pwrite(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, BDRV_SECTOR_SIZE, 0) < 0) { FLOPPY_DPRINTF("error writing sector %d\n", fd_sector(cur_drv));