diff --git a/debian/patches/extra/0037-block-reqlist-allow-adding-overlapping-requests.patch b/debian/patches/extra/0037-block-reqlist-allow-adding-overlapping-requests.patch new file mode 100644 index 0000000..3a9e131 --- /dev/null +++ b/debian/patches/extra/0037-block-reqlist-allow-adding-overlapping-requests.patch @@ -0,0 +1,104 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Fiona Ebner +Date: Thu, 7 Nov 2024 17:51:13 +0100 +Subject: [PATCH] block/reqlist: allow adding overlapping requests + +Allow overlapping request by removing the assert that made it +impossible. There are only two callers: + +1. block_copy_task_create() + +It already asserts the very same condition before calling +reqlist_init_req(). + +2. cbw_snapshot_read_lock() + +There is no need to have read requests be non-overlapping in +copy-before-write when used for snapshot-access. In fact, there was no +protection against two callers of cbw_snapshot_read_lock() calling +reqlist_init_req() with overlapping ranges and this could lead to an +assertion failure [1]. + +In particular, with the reproducer script below [0], two +cbw_co_snapshot_block_status() callers could race, with the second +calling reqlist_init_req() before the first one finishes and removes +its conflicting request. + +[0]: + +> #!/bin/bash -e +> dd if=/dev/urandom of=/tmp/disk.raw bs=1M count=1024 +> ./qemu-img create /tmp/fleecing.raw -f raw 1G +> ( +> ./qemu-system-x86_64 --qmp stdio \ +> --blockdev raw,node-name=node0,file.driver=file,file.filename=/tmp/disk.raw \ +> --blockdev raw,node-name=node1,file.driver=file,file.filename=/tmp/fleecing.raw \ +> < {"execute": "qmp_capabilities"} +> {"execute": "blockdev-add", "arguments": { "driver": "copy-before-write", "file": "node0", "target": "node1", "node-name": "node3" } } +> {"execute": "blockdev-add", "arguments": { "driver": "snapshot-access", "file": "node3", "node-name": "snap0" } } +> {"execute": "nbd-server-start", "arguments": {"addr": { "type": "unix", "data": { "path": "/tmp/nbd.socket" } } } } +> {"execute": "block-export-add", "arguments": {"id": "exp0", "node-name": "snap0", "type": "nbd", "name": "exp0"}} +> EOF +> ) & +> sleep 5 +> while true; do +> ./qemu-nbd -d /dev/nbd0 +> ./qemu-nbd -c /dev/nbd0 nbd:unix:/tmp/nbd.socket:exportname=exp0 -f raw -r +> nbdinfo --map 'nbd+unix:///exp0?socket=/tmp/nbd.socket' +> done + +[1]: + +> #5 0x000071e5f0088eb2 in __GI___assert_fail (...) at ./assert/assert.c:101 +> #6 0x0000615285438017 in reqlist_init_req (...) at ../block/reqlist.c:23 +> #7 0x00006152853e2d98 in cbw_snapshot_read_lock (...) at ../block/copy-before-write.c:237 +> #8 0x00006152853e3068 in cbw_co_snapshot_block_status (...) at ../block/copy-before-write.c:304 +> #9 0x00006152853f4d22 in bdrv_co_snapshot_block_status (...) at ../block/io.c:3726 +> #10 0x000061528543a63e in snapshot_access_co_block_status (...) at ../block/snapshot-access.c:48 +> #11 0x00006152853f1a0a in bdrv_co_do_block_status (...) at ../block/io.c:2474 +> #12 0x00006152853f2016 in bdrv_co_common_block_status_above (...) at ../block/io.c:2652 +> #13 0x00006152853f22cf in bdrv_co_block_status_above (...) at ../block/io.c:2732 +> #14 0x00006152853d9a86 in blk_co_block_status_above (...) at ../block/block-backend.c:1473 +> #15 0x000061528538da6c in blockstatus_to_extents (...) at ../nbd/server.c:2374 +> #16 0x000061528538deb1 in nbd_co_send_block_status (...) at ../nbd/server.c:2481 +> #17 0x000061528538f424 in nbd_handle_request (...) at ../nbd/server.c:2978 +> #18 0x000061528538f906 in nbd_trip (...) at ../nbd/server.c:3121 +> #19 0x00006152855a7caf in coroutine_trampoline (...) at ../util/coroutine-ucontext.c:175 + +Cc: qemu-stable@nongnu.org +Suggested-by: Vladimir Sementsov-Ogievskiy +Signed-off-by: Fiona Ebner +Reviewed-by: Vladimir Sementsov-Ogievskiy +--- + block/copy-before-write.c | 3 ++- + block/reqlist.c | 2 -- + 2 files changed, 2 insertions(+), 3 deletions(-) + +diff --git a/block/copy-before-write.c b/block/copy-before-write.c +index 8aba27a71d..3698b3bc60 100644 +--- a/block/copy-before-write.c ++++ b/block/copy-before-write.c +@@ -65,7 +65,8 @@ typedef struct BDRVCopyBeforeWriteState { + + /* + * @frozen_read_reqs: current read requests for fleecing user in bs->file +- * node. These areas must not be rewritten by guest. ++ * node. These areas must not be rewritten by guest. There can be multiple ++ * overlapping read requests. + */ + BlockReqList frozen_read_reqs; + +diff --git a/block/reqlist.c b/block/reqlist.c +index 08cb57cfa4..098e807378 100644 +--- a/block/reqlist.c ++++ b/block/reqlist.c +@@ -20,8 +20,6 @@ + void reqlist_init_req(BlockReqList *reqs, BlockReq *req, int64_t offset, + int64_t bytes) + { +- assert(!reqlist_find_conflict(reqs, offset, bytes)); +- + *req = (BlockReq) { + .offset = offset, + .bytes = bytes, diff --git a/debian/patches/series b/debian/patches/series index 9283156..4c53d28 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -34,6 +34,7 @@ extra/0033-nbd-server-CVE-2024-7409-Close-stray-clients-at-serv.patch extra/0034-vnc-fix-crash-when-no-console-attached.patch extra/0035-nbd-server-CVE-2024-7409-Avoid-use-after-free-when-c.patch extra/0036-softmmu-physmem-fix-memory-leak-in-dirty_memory_exte.patch +extra/0037-block-reqlist-allow-adding-overlapping-requests.patch bitmap-mirror/0001-drive-mirror-add-support-for-sync-bitmap-mode-never.patch bitmap-mirror/0002-drive-mirror-add-support-for-conditional-and-always-.patch bitmap-mirror/0003-mirror-add-check-for-bitmap-mode-without-bitmap.patch