[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [qemu-xen stable-4.6] xen/disk: don't leak stack data via response ring
commit 4e35ab1edd74b7d24b7a4aaebe75fe68222a2f2b Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Wed Jun 21 16:43:09 2017 +0100 Commit: Anthony PERARD <anthony.perard@xxxxxxxxxx> CommitDate: Wed Jun 21 16:43:09 2017 +0100 xen/disk: don't leak stack data via response ring Rather than constructing a local structure instance on the stack, fill the fields directly on the shared ring, just like other (Linux) backends do. Build on the fact that all response structure flavors are actually identical (the old code did make this assumption too). This is XSA-216. Reported-by: Anthony Perard <anthony.perard@xxxxxxxxxx> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx> --- hw/block/xen_blkif.h | 24 ++++++------------------ hw/block/xen_disk.c | 25 ++++++++++++------------- 2 files changed, 18 insertions(+), 31 deletions(-) diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h index c68487cb..5962f23 100644 --- a/hw/block/xen_blkif.h +++ b/hw/block/xen_blkif.h @@ -12,9 +12,6 @@ struct blkif_common_request { char dummy; }; -struct blkif_common_response { - char dummy; -}; /* i386 protocol version */ #pragma pack(push, 4) @@ -26,13 +23,7 @@ struct blkif_x86_32_request { blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; }; -struct blkif_x86_32_response { - uint64_t id; /* copied from request */ - uint8_t operation; /* copied from request */ - int16_t status; /* BLKIF_RSP_??? */ -}; typedef struct blkif_x86_32_request blkif_x86_32_request_t; -typedef struct blkif_x86_32_response blkif_x86_32_response_t; #pragma pack(pop) /* x86_64 protocol version */ @@ -44,17 +35,14 @@ struct blkif_x86_64_request { blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; }; -struct blkif_x86_64_response { - uint64_t __attribute__((__aligned__(8))) id; - uint8_t operation; /* copied from request */ - int16_t status; /* BLKIF_RSP_??? */ -}; typedef struct blkif_x86_64_request blkif_x86_64_request_t; -typedef struct blkif_x86_64_response blkif_x86_64_response_t; -DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, struct blkif_common_response); -DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct blkif_x86_32_response); -DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct blkif_x86_64_response); +DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, + struct blkif_response); +DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, + struct blkif_response QEMU_PACKED); +DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, + struct blkif_response); union blkif_back_rings { blkif_back_ring_t native; diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 21842a0..ae9f50f 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -612,31 +612,30 @@ static int blk_send_response_one(struct ioreq *ioreq) struct XenBlkDev *blkdev = ioreq->blkdev; int send_notify = 0; int have_requests = 0; - blkif_response_t resp; - void *dst; - - resp.id = ioreq->req.id; - resp.operation = ioreq->req.operation; - resp.status = ioreq->status; + blkif_response_t *resp; /* Place on the response ring for the relevant domain. */ switch (blkdev->protocol) { case BLKIF_PROTOCOL_NATIVE: - dst = RING_GET_RESPONSE(&blkdev->rings.native, blkdev->rings.native.rsp_prod_pvt); + resp = RING_GET_RESPONSE(&blkdev->rings.native, + blkdev->rings.native.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_32: - dst = RING_GET_RESPONSE(&blkdev->rings.x86_32_part, - blkdev->rings.x86_32_part.rsp_prod_pvt); + resp = RING_GET_RESPONSE(&blkdev->rings.x86_32_part, + blkdev->rings.x86_32_part.rsp_prod_pvt); break; case BLKIF_PROTOCOL_X86_64: - dst = RING_GET_RESPONSE(&blkdev->rings.x86_64_part, - blkdev->rings.x86_64_part.rsp_prod_pvt); + resp = RING_GET_RESPONSE(&blkdev->rings.x86_64_part, + blkdev->rings.x86_64_part.rsp_prod_pvt); break; default: - dst = NULL; return 0; } - memcpy(dst, &resp, sizeof(resp)); + + resp->id = ioreq->req.id; + resp->operation = ioreq->req.operation; + resp->status = ioreq->status; + blkdev->rings.common.rsp_prod_pvt++; RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blkdev->rings.common, send_notify); -- generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.6 _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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