From: P J P <ppandit@redhat.com>
To: John Snow <jsnow@redhat.com>
Cc: Ruhr-University <bugs-syssec@rub.de>,
QEMU Developers <qemu-devel@nongnu.org>,
qemu-block@nongnu.org, Prasad J Pandit <pjp@fedoraproject.org>
Subject: [PATCH] fdc: check null block pointer before blk_pwrite
Date: Thu, 27 Aug 2020 17:08:06 +0530 [thread overview]
Message-ID: <20200827113806.1850687-1-ppandit@redhat.com> (raw)
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));
--
2.26.2
next reply other threads:[~2020-08-27 11:41 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 11:38 P J P [this message]
2020-09-15 12:47 ` [PATCH] fdc: check null block pointer before blk_pwrite P J P
2020-09-18 10:52 ` Li Qiang
2021-03-19 5:09 ` [PATCH 1/2] floppy: add a regression test for CVE-2020-25741 Alexander Bulekov
2021-03-19 5:09 ` [PATCH 2/2] floppy: add a regression test for CVE-2021-20196 Alexander Bulekov
2021-03-19 5:53 ` [PATCH 1/2] floppy: add a regression test for CVE-2020-25741 Markus Armbruster
2021-03-19 9:26 ` Paolo Bonzini
2021-03-19 9:54 ` Markus Armbruster
2021-03-19 10:17 ` Paolo Bonzini
2021-03-19 14:51 ` Alexander Bulekov
2021-03-19 14:52 ` Alexander Bulekov
2021-05-18 17:30 ` [PATCH] fdc: check null block pointer before blk_pwrite John Snow
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