304d5426c4
fix CVE-2020-25743 patch link: https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05967.html When canceling an i/o operation via ide_cancel_dam_sync(), a block pointer may be null. Add check to avoid null pointer dereference. -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fide_nullptr1 ==1803100==Hint: address points to the zero page. #0 blk_bs ../block/block-backend.c:714 #1 blk_drain ../block/block-backend.c:1715 #2 ide_cancel_dma_sync ../hw/ide/core.c:723 #3 bmdma_cmd_writeb ../hw/ide/core.c:723 #4 bmdma_write ../hw/ide/pci.c:298 #5 memory_region_write_accessor ../softmmu/memory.c:483 #6 access_with_adjusted_size ../softmmu/memory.c:544 #7 memory_region_dispatch_write ../softmmu/memory.c:1465 #8 flatview_write_continue ../exe.c:3176 ... Reported-by: Ruhr-University <bugs-syssec@rub.de> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
65 lines
2.2 KiB
Diff
65 lines
2.2 KiB
Diff
From 3b23698e240bd0efe987cf113e3bc8d233991d21 Mon Sep 17 00:00:00 2001
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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Wed, 14 Oct 2020 15:57:18 +0800
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Subject: [PATCH] hw/ide: check null block before _cancel_dma_sync
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fix CVE-2020-25743
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patch link: https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05967.html
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When canceling an i/o operation via ide_cancel_dam_sync(),
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a block pointer may be null. Add check to avoid null pointer
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dereference.
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-> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fide_nullptr1
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==1803100==Hint: address points to the zero page.
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#0 blk_bs ../block/block-backend.c:714
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#1 blk_drain ../block/block-backend.c:1715
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#2 ide_cancel_dma_sync ../hw/ide/core.c:723
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#3 bmdma_cmd_writeb ../hw/ide/core.c:723
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#4 bmdma_write ../hw/ide/pci.c:298
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#5 memory_region_write_accessor ../softmmu/memory.c:483
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#6 access_with_adjusted_size ../softmmu/memory.c:544
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#7 memory_region_dispatch_write ../softmmu/memory.c:1465
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#8 flatview_write_continue ../exe.c:3176
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...
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Reported-by: Ruhr-University <bugs-syssec@rub.de>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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---
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hw/ide/core.c | 1 +
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hw/ide/pci.c | 5 ++++-
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2 files changed, 5 insertions(+), 1 deletion(-)
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diff --git a/hw/ide/core.c b/hw/ide/core.c
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index f76f7e5234..8105187f49 100644
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--- a/hw/ide/core.c
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+++ b/hw/ide/core.c
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@@ -718,6 +718,7 @@ void ide_cancel_dma_sync(IDEState *s)
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* whole DMA operation will be submitted to disk with a single
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* aio operation with preadv/pwritev.
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*/
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+ assert(s->blk);
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if (s->bus->dma->aiocb) {
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trace_ide_cancel_dma_sync_remaining();
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blk_drain(s->blk);
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diff --git a/hw/ide/pci.c b/hw/ide/pci.c
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index b50091b615..b47e675456 100644
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--- a/hw/ide/pci.c
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+++ b/hw/ide/pci.c
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@@ -295,7 +295,10 @@ void bmdma_cmd_writeb(BMDMAState *bm, uint32_t val)
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/* Ignore writes to SSBM if it keeps the old value */
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if ((val & BM_CMD_START) != (bm->cmd & BM_CMD_START)) {
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if (!(val & BM_CMD_START)) {
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- ide_cancel_dma_sync(idebus_active_if(bm->bus));
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+ IDEState *s = idebus_active_if(bm->bus);
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+ if (s->blk) {
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+ ide_cancel_dma_sync(s);
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+ }
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bm->status &= ~BM_STATUS_DMAING;
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} else {
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bm->cur_addr = bm->addr;
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--
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2.23.0
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