From: Liu Shixin <liushixin2@huawei.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5EZK8 CVE: NA -------------------------------- After patch ddbd89deb7d3 ("swiotlb: fix info leak with DMA_FROM_DEVICE"), swiotlb_bounce will be called in swiotlb_tbl_map_single unconditionally. This requires that the physical address must be valid, which is not always true on stable-4.19 or earlier version. On stable-4.19, swiotlb_alloc_buffer will call swiotlb_tbl_map_single with orig_addr equal to zero, which cause such a panic: Unable to handle kernel paging request at virtual address ffffb77a40000000 ... pc : __memcpy+0x100/0x180 lr : swiotlb_bounce+0x74/0x88 ... Call trace: __memcpy+0x100/0x180 swiotlb_tbl_map_single+0x2c8/0x338 swiotlb_alloc+0xb4/0x198 __dma_alloc+0x84/0x1d8 ... On stable-4.9 and stable-4.14, swiotlb_alloc_coherent wille call map_single with orig_addr equal to zero, which can cause same panic. Fix this by skipping swiotlb_bounce when orig_addr is zero. Fixes: ddbd89deb7d3 ("swiotlb: fix info leak with DMA_FROM_DEVICE") Signed-off-by: Liu Shixin <liushixin2@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- kernel/dma/swiotlb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 694e7ccea659..8059f83bbe48 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -590,7 +590,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, * unconditional bounce may prevent leaking swiotlb content (i.e. * kernel memory) to user-space. */ - swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE); + if (orig_addr) + swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE); return tlb_addr; } -- 2.25.1