| Message ID | 20210916093350.1410403-1-yukuai3@huawei.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | handle unexpected message from server | expand |
On 2021/09/16 17:33, Yu Kuai wrote: Hi, jens Any interest to apply this series? Thanks, Kuai > This patch set tries to fix that client might oops if nbd server send > unexpected message to client, for example, our syzkaller report a uaf > in nbd_read_stat(): > > Call trace: > dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 > show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x144/0x1b4 lib/dump_stack.c:118 > print_address_description+0x68/0x2d0 mm/kasan/report.c:253 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x134/0x2f0 mm/kasan/report.c:409 > check_memory_region_inline mm/kasan/kasan.c:260 [inline] > __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 > __read_once_size include/linux/compiler.h:193 [inline] > blk_mq_rq_state block/blk-mq.h:106 [inline] > blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 > nbd_read_stat drivers/block/nbd.c:670 [inline] > recv_work+0x1bc/0x890 drivers/block/nbd.c:749 > process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 > worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 > kthread+0x1d8/0x1e0 kernel/kthread.c:255 > ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 > > 1) At first, a normal io is submitted and completed with scheduler: > > internel_tag = blk_mq_get_tag -> get tag from sched_tags > blk_mq_rq_ctx_init > sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] > ... > blk_mq_get_driver_tag > __blk_mq_get_driver_tag -> get tag from tags > tags->rq[tag] = sched_tag->static_rq[internel_tag] > > So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing > to the request: sched_tags->static_rq[internal_tag]. Even if the > io is finished. > > 2) nbd server send a reply with random tag directly: > > recv_work > nbd_read_stat > blk_mq_tag_to_rq(tags, tag) > rq = tags->rq[tag] > > 3) if the sched_tags->static_rq is freed: > > blk_mq_sched_free_requests > blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) > -> step 2) access rq before clearing rq mapping > blk_mq_clear_rq_mapping(set, tags, hctx_idx); > __free_pages() -> rq is freed here > > 4) Then, nbd continue to use the freed request in nbd_read_stat() > > Changes in v8: > - add patch 5 to this series. > - modify some words. > Changes in v7: > - instead of exposing blk_queue_exit(), using percpu_ref_put() > directly. > - drop the ref right after nbd_handle_reply(). > Changes in v6: > - don't set cmd->status to error if request is completed before > nbd_clear_req(). > - get 'q_usage_counter' to prevent accessing freed request through > blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). > Changes in v5: > - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind > - add some comment in patch 5 > Changes in v4: > - change the name of the patchset, since uaf is not the only problem > if server send unexpected reply message. > - instead of adding new interface, use blk_mq_find_and_get_req(). > - add patch 5 to this series > Changes in v3: > - v2 can't fix the problem thoroughly, add patch 3-4 to this series. > - modify descriptions. > - patch 5 is just a cleanup > Changes in v2: > - as Bart suggested, add a new helper function for drivers to get > request by tag. > > Yu Kuai (7): > nbd: don't handle response without a corresponding request message > nbd: make sure request completion won't concurrent > nbd: check sock index in nbd_read_stat() > nbd: don't start request if nbd_queue_rq() failed > nbd: clean up return value checking of sock_xmit() > nbd: partition nbd_read_stat() into nbd_read_reply() and > nbd_handle_reply() > nbd: fix uaf in nbd_handle_reply() > > drivers/block/nbd.c | 135 +++++++++++++++++++++++++++++++------------- > 1 file changed, 96 insertions(+), 39 deletions(-) >
On 2021/09/23 21:33, yukuai (C) wrote: > On 2021/09/16 17:33, Yu Kuai wrote: > > Hi, jens > > Any interest to apply this series? friendly ping ... > > Thanks, > Kuai >> This patch set tries to fix that client might oops if nbd server send >> unexpected message to client, for example, our syzkaller report a uaf >> in nbd_read_stat(): >> >> Call trace: >> dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 >> show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x144/0x1b4 lib/dump_stack.c:118 >> print_address_description+0x68/0x2d0 mm/kasan/report.c:253 >> kasan_report_error mm/kasan/report.c:351 [inline] >> kasan_report+0x134/0x2f0 mm/kasan/report.c:409 >> check_memory_region_inline mm/kasan/kasan.c:260 [inline] >> __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 >> __read_once_size include/linux/compiler.h:193 [inline] >> blk_mq_rq_state block/blk-mq.h:106 [inline] >> blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 >> nbd_read_stat drivers/block/nbd.c:670 [inline] >> recv_work+0x1bc/0x890 drivers/block/nbd.c:749 >> process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 >> worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 >> kthread+0x1d8/0x1e0 kernel/kthread.c:255 >> ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 >> >> 1) At first, a normal io is submitted and completed with scheduler: >> >> internel_tag = blk_mq_get_tag -> get tag from sched_tags >> blk_mq_rq_ctx_init >> sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] >> ... >> blk_mq_get_driver_tag >> __blk_mq_get_driver_tag -> get tag from tags >> tags->rq[tag] = sched_tag->static_rq[internel_tag] >> >> So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing >> to the request: sched_tags->static_rq[internal_tag]. Even if the >> io is finished. >> >> 2) nbd server send a reply with random tag directly: >> >> recv_work >> nbd_read_stat >> blk_mq_tag_to_rq(tags, tag) >> rq = tags->rq[tag] >> >> 3) if the sched_tags->static_rq is freed: >> >> blk_mq_sched_free_requests >> blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) >> -> step 2) access rq before clearing rq mapping >> blk_mq_clear_rq_mapping(set, tags, hctx_idx); >> __free_pages() -> rq is freed here >> >> 4) Then, nbd continue to use the freed request in nbd_read_stat() >> >> Changes in v8: >> - add patch 5 to this series. >> - modify some words. >> Changes in v7: >> - instead of exposing blk_queue_exit(), using percpu_ref_put() >> directly. >> - drop the ref right after nbd_handle_reply(). >> Changes in v6: >> - don't set cmd->status to error if request is completed before >> nbd_clear_req(). >> - get 'q_usage_counter' to prevent accessing freed request through >> blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). >> Changes in v5: >> - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind >> - add some comment in patch 5 >> Changes in v4: >> - change the name of the patchset, since uaf is not the only problem >> if server send unexpected reply message. >> - instead of adding new interface, use blk_mq_find_and_get_req(). >> - add patch 5 to this series >> Changes in v3: >> - v2 can't fix the problem thoroughly, add patch 3-4 to this series. >> - modify descriptions. >> - patch 5 is just a cleanup >> Changes in v2: >> - as Bart suggested, add a new helper function for drivers to get >> request by tag. >> >> Yu Kuai (7): >> nbd: don't handle response without a corresponding request message >> nbd: make sure request completion won't concurrent >> nbd: check sock index in nbd_read_stat() >> nbd: don't start request if nbd_queue_rq() failed >> nbd: clean up return value checking of sock_xmit() >> nbd: partition nbd_read_stat() into nbd_read_reply() and >> nbd_handle_reply() >> nbd: fix uaf in nbd_handle_reply() >> >> drivers/block/nbd.c | 135 +++++++++++++++++++++++++++++++------------- >> 1 file changed, 96 insertions(+), 39 deletions(-) >>
On 2021/09/29 20:54, yukuai (C) wrote: > On 2021/09/23 21:33, yukuai (C) wrote: >> On 2021/09/16 17:33, Yu Kuai wrote: >> >> Hi, jens >> >> Any interest to apply this series? > > friendly ping ... Hi, Jens friendly ping again ... >> >> Thanks, >> Kuai >>> This patch set tries to fix that client might oops if nbd server send >>> unexpected message to client, for example, our syzkaller report a uaf >>> in nbd_read_stat(): >>> >>> Call trace: >>> dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 >>> show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 >>> __dump_stack lib/dump_stack.c:77 [inline] >>> dump_stack+0x144/0x1b4 lib/dump_stack.c:118 >>> print_address_description+0x68/0x2d0 mm/kasan/report.c:253 >>> kasan_report_error mm/kasan/report.c:351 [inline] >>> kasan_report+0x134/0x2f0 mm/kasan/report.c:409 >>> check_memory_region_inline mm/kasan/kasan.c:260 [inline] >>> __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 >>> __read_once_size include/linux/compiler.h:193 [inline] >>> blk_mq_rq_state block/blk-mq.h:106 [inline] >>> blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 >>> nbd_read_stat drivers/block/nbd.c:670 [inline] >>> recv_work+0x1bc/0x890 drivers/block/nbd.c:749 >>> process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 >>> worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 >>> kthread+0x1d8/0x1e0 kernel/kthread.c:255 >>> ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 >>> >>> 1) At first, a normal io is submitted and completed with scheduler: >>> >>> internel_tag = blk_mq_get_tag -> get tag from sched_tags >>> blk_mq_rq_ctx_init >>> sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] >>> ... >>> blk_mq_get_driver_tag >>> __blk_mq_get_driver_tag -> get tag from tags >>> tags->rq[tag] = sched_tag->static_rq[internel_tag] >>> >>> So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing >>> to the request: sched_tags->static_rq[internal_tag]. Even if the >>> io is finished. >>> >>> 2) nbd server send a reply with random tag directly: >>> >>> recv_work >>> nbd_read_stat >>> blk_mq_tag_to_rq(tags, tag) >>> rq = tags->rq[tag] >>> >>> 3) if the sched_tags->static_rq is freed: >>> >>> blk_mq_sched_free_requests >>> blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) >>> -> step 2) access rq before clearing rq mapping >>> blk_mq_clear_rq_mapping(set, tags, hctx_idx); >>> __free_pages() -> rq is freed here >>> >>> 4) Then, nbd continue to use the freed request in nbd_read_stat() >>> >>> Changes in v8: >>> - add patch 5 to this series. >>> - modify some words. >>> Changes in v7: >>> - instead of exposing blk_queue_exit(), using percpu_ref_put() >>> directly. >>> - drop the ref right after nbd_handle_reply(). >>> Changes in v6: >>> - don't set cmd->status to error if request is completed before >>> nbd_clear_req(). >>> - get 'q_usage_counter' to prevent accessing freed request through >>> blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). >>> Changes in v5: >>> - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind >>> - add some comment in patch 5 >>> Changes in v4: >>> - change the name of the patchset, since uaf is not the only problem >>> if server send unexpected reply message. >>> - instead of adding new interface, use blk_mq_find_and_get_req(). >>> - add patch 5 to this series >>> Changes in v3: >>> - v2 can't fix the problem thoroughly, add patch 3-4 to this series. >>> - modify descriptions. >>> - patch 5 is just a cleanup >>> Changes in v2: >>> - as Bart suggested, add a new helper function for drivers to get >>> request by tag. >>> >>> Yu Kuai (7): >>> nbd: don't handle response without a corresponding request message >>> nbd: make sure request completion won't concurrent >>> nbd: check sock index in nbd_read_stat() >>> nbd: don't start request if nbd_queue_rq() failed >>> nbd: clean up return value checking of sock_xmit() >>> nbd: partition nbd_read_stat() into nbd_read_reply() and >>> nbd_handle_reply() >>> nbd: fix uaf in nbd_handle_reply() >>> >>> drivers/block/nbd.c | 135 +++++++++++++++++++++++++++++++------------- >>> 1 file changed, 96 insertions(+), 39 deletions(-) >>>
On 2021/10/08 15:17, yukuai (C) wrote: > On 2021/09/29 20:54, yukuai (C) wrote: >> On 2021/09/23 21:33, yukuai (C) wrote: >>> On 2021/09/16 17:33, Yu Kuai wrote: >>> >>> Hi, jens >>> >>> Any interest to apply this series? >> >> friendly ping ... > > Hi, Jens > > friendly ping again ... Hi, Jens friendly ping again ... >>> >>> Thanks, >>> Kuai >>>> This patch set tries to fix that client might oops if nbd server send >>>> unexpected message to client, for example, our syzkaller report a uaf >>>> in nbd_read_stat(): >>>> >>>> Call trace: >>>> dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 >>>> show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 >>>> __dump_stack lib/dump_stack.c:77 [inline] >>>> dump_stack+0x144/0x1b4 lib/dump_stack.c:118 >>>> print_address_description+0x68/0x2d0 mm/kasan/report.c:253 >>>> kasan_report_error mm/kasan/report.c:351 [inline] >>>> kasan_report+0x134/0x2f0 mm/kasan/report.c:409 >>>> check_memory_region_inline mm/kasan/kasan.c:260 [inline] >>>> __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 >>>> __read_once_size include/linux/compiler.h:193 [inline] >>>> blk_mq_rq_state block/blk-mq.h:106 [inline] >>>> blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 >>>> nbd_read_stat drivers/block/nbd.c:670 [inline] >>>> recv_work+0x1bc/0x890 drivers/block/nbd.c:749 >>>> process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 >>>> worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 >>>> kthread+0x1d8/0x1e0 kernel/kthread.c:255 >>>> ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 >>>> >>>> 1) At first, a normal io is submitted and completed with scheduler: >>>> >>>> internel_tag = blk_mq_get_tag -> get tag from sched_tags >>>> blk_mq_rq_ctx_init >>>> sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] >>>> ... >>>> blk_mq_get_driver_tag >>>> __blk_mq_get_driver_tag -> get tag from tags >>>> tags->rq[tag] = sched_tag->static_rq[internel_tag] >>>> >>>> So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing >>>> to the request: sched_tags->static_rq[internal_tag]. Even if the >>>> io is finished. >>>> >>>> 2) nbd server send a reply with random tag directly: >>>> >>>> recv_work >>>> nbd_read_stat >>>> blk_mq_tag_to_rq(tags, tag) >>>> rq = tags->rq[tag] >>>> >>>> 3) if the sched_tags->static_rq is freed: >>>> >>>> blk_mq_sched_free_requests >>>> blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) >>>> -> step 2) access rq before clearing rq mapping >>>> blk_mq_clear_rq_mapping(set, tags, hctx_idx); >>>> __free_pages() -> rq is freed here >>>> >>>> 4) Then, nbd continue to use the freed request in nbd_read_stat() >>>> >>>> Changes in v8: >>>> - add patch 5 to this series. >>>> - modify some words. >>>> Changes in v7: >>>> - instead of exposing blk_queue_exit(), using percpu_ref_put() >>>> directly. >>>> - drop the ref right after nbd_handle_reply(). >>>> Changes in v6: >>>> - don't set cmd->status to error if request is completed before >>>> nbd_clear_req(). >>>> - get 'q_usage_counter' to prevent accessing freed request through >>>> blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). >>>> Changes in v5: >>>> - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind >>>> - add some comment in patch 5 >>>> Changes in v4: >>>> - change the name of the patchset, since uaf is not the only problem >>>> if server send unexpected reply message. >>>> - instead of adding new interface, use blk_mq_find_and_get_req(). >>>> - add patch 5 to this series >>>> Changes in v3: >>>> - v2 can't fix the problem thoroughly, add patch 3-4 to this series. >>>> - modify descriptions. >>>> - patch 5 is just a cleanup >>>> Changes in v2: >>>> - as Bart suggested, add a new helper function for drivers to get >>>> request by tag. >>>> >>>> Yu Kuai (7): >>>> nbd: don't handle response without a corresponding request message >>>> nbd: make sure request completion won't concurrent >>>> nbd: check sock index in nbd_read_stat() >>>> nbd: don't start request if nbd_queue_rq() failed >>>> nbd: clean up return value checking of sock_xmit() >>>> nbd: partition nbd_read_stat() into nbd_read_reply() and >>>> nbd_handle_reply() >>>> nbd: fix uaf in nbd_handle_reply() >>>> >>>> drivers/block/nbd.c | 135 >>>> +++++++++++++++++++++++++++++++------------- >>>> 1 file changed, 96 insertions(+), 39 deletions(-) >>>>
On Thu, Sep 16, 2021 at 05:33:43PM +0800, Yu Kuai wrote: > This patch set tries to fix that client might oops if nbd server send > unexpected message to client, for example, our syzkaller report a uaf > in nbd_read_stat(): > > Call trace: > dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 > show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x144/0x1b4 lib/dump_stack.c:118 > print_address_description+0x68/0x2d0 mm/kasan/report.c:253 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x134/0x2f0 mm/kasan/report.c:409 > check_memory_region_inline mm/kasan/kasan.c:260 [inline] > __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 > __read_once_size include/linux/compiler.h:193 [inline] > blk_mq_rq_state block/blk-mq.h:106 [inline] > blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 > nbd_read_stat drivers/block/nbd.c:670 [inline] > recv_work+0x1bc/0x890 drivers/block/nbd.c:749 > process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 > worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 > kthread+0x1d8/0x1e0 kernel/kthread.c:255 > ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 > > 1) At first, a normal io is submitted and completed with scheduler: > > internel_tag = blk_mq_get_tag -> get tag from sched_tags > blk_mq_rq_ctx_init > sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] > ... > blk_mq_get_driver_tag > __blk_mq_get_driver_tag -> get tag from tags > tags->rq[tag] = sched_tag->static_rq[internel_tag] > > So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing > to the request: sched_tags->static_rq[internal_tag]. Even if the > io is finished. > > 2) nbd server send a reply with random tag directly: > > recv_work > nbd_read_stat > blk_mq_tag_to_rq(tags, tag) > rq = tags->rq[tag] > > 3) if the sched_tags->static_rq is freed: > > blk_mq_sched_free_requests > blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) > -> step 2) access rq before clearing rq mapping > blk_mq_clear_rq_mapping(set, tags, hctx_idx); > __free_pages() -> rq is freed here > > 4) Then, nbd continue to use the freed request in nbd_read_stat() > > Changes in v8: > - add patch 5 to this series. > - modify some words. > Changes in v7: > - instead of exposing blk_queue_exit(), using percpu_ref_put() > directly. > - drop the ref right after nbd_handle_reply(). > Changes in v6: > - don't set cmd->status to error if request is completed before > nbd_clear_req(). > - get 'q_usage_counter' to prevent accessing freed request through > blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). > Changes in v5: > - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind > - add some comment in patch 5 > Changes in v4: > - change the name of the patchset, since uaf is not the only problem > if server send unexpected reply message. > - instead of adding new interface, use blk_mq_find_and_get_req(). > - add patch 5 to this series > Changes in v3: > - v2 can't fix the problem thoroughly, add patch 3-4 to this series. > - modify descriptions. > - patch 5 is just a cleanup > Changes in v2: > - as Bart suggested, add a new helper function for drivers to get > request by tag. > You can add Reviewed-by: Josef Bacik <josef@toxicpanda.com> to the series. Sorry Jens, this one slipped through the cracks. Thanks, Josef
On Thu, 16 Sep 2021 17:33:43 +0800, Yu Kuai wrote: > This patch set tries to fix that client might oops if nbd server send > unexpected message to client, for example, our syzkaller report a uaf > in nbd_read_stat(): > > Call trace: > dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 > show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x144/0x1b4 lib/dump_stack.c:118 > print_address_description+0x68/0x2d0 mm/kasan/report.c:253 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x134/0x2f0 mm/kasan/report.c:409 > check_memory_region_inline mm/kasan/kasan.c:260 [inline] > __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 > __read_once_size include/linux/compiler.h:193 [inline] > blk_mq_rq_state block/blk-mq.h:106 [inline] > blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 > nbd_read_stat drivers/block/nbd.c:670 [inline] > recv_work+0x1bc/0x890 drivers/block/nbd.c:749 > process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 > worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 > kthread+0x1d8/0x1e0 kernel/kthread.c:255 > ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 > > [...] Applied, thanks! [1/7] nbd: don't handle response without a corresponding request message commit: b5644a3a79bf3be5f1238db1b2f241374b27b0f0 [2/7] nbd: make sure request completion won't concurrent commit: d14b304f558f8c8f53da3a8d0c0b671f14a9c2f4 [3/7] nbd: check sock index in nbd_read_stat() commit: dbd73178da676945d8bbcf6afe731623f683ce0a [4/7] nbd: don't start request if nbd_queue_rq() failed commit: a83fdc85365586dc5c0f3ff91680e18e37a66f19 [5/7] nbd: clean up return value checking of sock_xmit() commit: 6157a8f489909db00151a4e361903b9099b03b75 [6/7] nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply() commit: 961e9f50be9bb47835b0ac7e08d55d2d0a45e493 [7/7] nbd: fix uaf in nbd_handle_reply() commit: 52c90e0184f67eecb00b53b79bfdf75e0274f8fd Best regards,
This patch set tries to fix that client might oops if nbd server send unexpected message to client, for example, our syzkaller report a uaf in nbd_read_stat(): Call trace: dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x144/0x1b4 lib/dump_stack.c:118 print_address_description+0x68/0x2d0 mm/kasan/report.c:253 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x134/0x2f0 mm/kasan/report.c:409 check_memory_region_inline mm/kasan/kasan.c:260 [inline] __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 __read_once_size include/linux/compiler.h:193 [inline] blk_mq_rq_state block/blk-mq.h:106 [inline] blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 nbd_read_stat drivers/block/nbd.c:670 [inline] recv_work+0x1bc/0x890 drivers/block/nbd.c:749 process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 kthread+0x1d8/0x1e0 kernel/kthread.c:255 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 1) At first, a normal io is submitted and completed with scheduler: internel_tag = blk_mq_get_tag -> get tag from sched_tags blk_mq_rq_ctx_init sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] ... blk_mq_get_driver_tag __blk_mq_get_driver_tag -> get tag from tags tags->rq[tag] = sched_tag->static_rq[internel_tag] So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing to the request: sched_tags->static_rq[internal_tag]. Even if the io is finished. 2) nbd server send a reply with random tag directly: recv_work nbd_read_stat blk_mq_tag_to_rq(tags, tag) rq = tags->rq[tag] 3) if the sched_tags->static_rq is freed: blk_mq_sched_free_requests blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) -> step 2) access rq before clearing rq mapping blk_mq_clear_rq_mapping(set, tags, hctx_idx); __free_pages() -> rq is freed here 4) Then, nbd continue to use the freed request in nbd_read_stat() Changes in v8: - add patch 5 to this series. - modify some words. Changes in v7: - instead of exposing blk_queue_exit(), using percpu_ref_put() directly. - drop the ref right after nbd_handle_reply(). Changes in v6: - don't set cmd->status to error if request is completed before nbd_clear_req(). - get 'q_usage_counter' to prevent accessing freed request through blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). Changes in v5: - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind - add some comment in patch 5 Changes in v4: - change the name of the patchset, since uaf is not the only problem if server send unexpected reply message. - instead of adding new interface, use blk_mq_find_and_get_req(). - add patch 5 to this series Changes in v3: - v2 can't fix the problem thoroughly, add patch 3-4 to this series. - modify descriptions. - patch 5 is just a cleanup Changes in v2: - as Bart suggested, add a new helper function for drivers to get request by tag. Yu Kuai (7): nbd: don't handle response without a corresponding request message nbd: make sure request completion won't concurrent nbd: check sock index in nbd_read_stat() nbd: don't start request if nbd_queue_rq() failed nbd: clean up return value checking of sock_xmit() nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply() nbd: fix uaf in nbd_handle_reply() drivers/block/nbd.c | 135 +++++++++++++++++++++++++++++++------------- 1 file changed, 96 insertions(+), 39 deletions(-)