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
Subject: Re: [PATCH] fdc: check null block pointer before blk_pwrite
Date: Tue, 15 Sep 2020 18:17:30 +0530 (IST) [thread overview]
Message-ID: <nycvar.YSQ.7.78.906.2009151817040.10832@xnncv> (raw)
In-Reply-To: <20200827113806.1850687-1-ppandit@redhat.com>
+-- 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
next prev parent reply other threads:[~2020-09-15 13:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 11:38 [PATCH] fdc: check null block pointer before blk_pwrite P J P
2020-09-15 12:47 ` P J P [this message]
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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