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[PATCH v2] fdc: check null block pointer before r/w data transfer
From: |
P J P |
Subject: |
[PATCH v2] fdc: check null block pointer before r/w data transfer |
Date: |
Tue, 22 Sep 2020 14:57:22 +0530 |
From: Prasad J Pandit <pjp@fedoraproject.org>
While transferring data via fdctrl_read/write_data() routines,
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 | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Update v2: treat NULL blk pointer as an error
-> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg06642.html
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 224bac504f..bf968dc66f 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1923,7 +1923,8 @@ static uint32_t fdctrl_read_data(FDCtrl *fdctrl)
fd_sector(cur_drv));
return 0;
}
- if (blk_pread(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo,
+ if (!cur_drv->blk
+ || blk_pread(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo,
BDRV_SECTOR_SIZE)
< 0) {
FLOPPY_DPRINTF("error getting sector %d\n",
@@ -2427,7 +2428,8 @@ 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));
--
2.26.2
- [PATCH v2] fdc: check null block pointer before r/w data transfer,
P J P <=