1 Commits

Author SHA1 Message Date
Prasad J Pandit
304d5426c4 hw/ide: check null block before _cancel_dma_sync
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>
2020-10-22 16:29:39 +08:00