Message ID | 20210909133737.1930835-1-lijinlin3@huawei.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | fix UAF in bfq_io_set_weight_legacy() | expand |
On 9/9/21 7:37 AM, Li Jinlin wrote: > From: Li Jinlin <lijinlin3@huawei.com> > > KASAN reports a use-after-free report when doing fuzz test: > > [693354.104835] ================================================================== > [693354.105094] BUG: KASAN: use-after-free in bfq_io_set_weight_legacy+0xd3/0x160 > [693354.105336] Read of size 4 at addr ffff888be0a35664 by task sh/1453338 > > [693354.105607] CPU: 41 PID: 1453338 Comm: sh Kdump: loaded Not tainted 4.18.0-147 > [693354.105610] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.81 07/02/2018 > [693354.105612] Call Trace: > [693354.105621] dump_stack+0xf1/0x19b > [693354.105626] ? show_regs_print_info+0x5/0x5 > [693354.105634] ? printk+0x9c/0xc3 > [693354.105638] ? cpumask_weight+0x1f/0x1f > [693354.105648] print_address_description+0x70/0x360 > [693354.105654] kasan_report+0x1b2/0x330 > [693354.105659] ? bfq_io_set_weight_legacy+0xd3/0x160 > [693354.105665] ? bfq_io_set_weight_legacy+0xd3/0x160 > [693354.105670] bfq_io_set_weight_legacy+0xd3/0x160 > [693354.105675] ? bfq_cpd_init+0x20/0x20 > [693354.105683] cgroup_file_write+0x3aa/0x510 > [693354.105693] ? ___slab_alloc+0x507/0x540 > [693354.105698] ? cgroup_file_poll+0x60/0x60 > [693354.105702] ? 0xffffffff89600000 > [693354.105708] ? usercopy_abort+0x90/0x90 > [693354.105716] ? mutex_lock+0xef/0x180 > [693354.105726] kernfs_fop_write+0x1ab/0x280 > [693354.105732] ? cgroup_file_poll+0x60/0x60 > [693354.105738] vfs_write+0xe7/0x230 > [693354.105744] ksys_write+0xb0/0x140 > [693354.105749] ? __ia32_sys_read+0x50/0x50 > [693354.105760] do_syscall_64+0x112/0x370 > [693354.105766] ? syscall_return_slowpath+0x260/0x260 > [693354.105772] ? do_page_fault+0x9b/0x270 > [693354.105779] ? prepare_exit_to_usermode+0xf9/0x1a0 > [693354.105784] ? enter_from_user_mode+0x30/0x30 > [693354.105793] entry_SYSCALL_64_after_hwframe+0x65/0xca > > [693354.105875] Allocated by task 1453337: > [693354.106001] kasan_kmalloc+0xa0/0xd0 > [693354.106006] kmem_cache_alloc_node_trace+0x108/0x220 > [693354.106010] bfq_pd_alloc+0x96/0x120 > [693354.106015] blkcg_activate_policy+0x1b7/0x2b0 > [693354.106020] bfq_create_group_hierarchy+0x1e/0x80 > [693354.106026] bfq_init_queue+0x678/0x8c0 > [693354.106031] blk_mq_init_sched+0x1f8/0x460 > [693354.106037] elevator_switch_mq+0xe1/0x240 > [693354.106041] elevator_switch+0x25/0x40 > [693354.106045] elv_iosched_store+0x1a1/0x230 > [693354.106049] queue_attr_store+0x78/0xb0 > [693354.106053] kernfs_fop_write+0x1ab/0x280 > [693354.106056] vfs_write+0xe7/0x230 > [693354.106060] ksys_write+0xb0/0x140 > [693354.106064] do_syscall_64+0x112/0x370 > [693354.106069] entry_SYSCALL_64_after_hwframe+0x65/0xca > > [693354.106114] Freed by task 1453336: > [693354.106225] __kasan_slab_free+0x130/0x180 > [693354.106229] kfree+0x90/0x1b0 > [693354.106233] blkcg_deactivate_policy+0x12c/0x220 > [693354.106238] bfq_exit_queue+0xf5/0x110 > [693354.106241] blk_mq_exit_sched+0x104/0x130 > [693354.106245] __elevator_exit+0x45/0x60 > [693354.106249] elevator_switch_mq+0xd6/0x240 > [693354.106253] elevator_switch+0x25/0x40 > [693354.106257] elv_iosched_store+0x1a1/0x230 > [693354.106261] queue_attr_store+0x78/0xb0 > [693354.106264] kernfs_fop_write+0x1ab/0x280 > [693354.106268] vfs_write+0xe7/0x230 > [693354.106271] ksys_write+0xb0/0x140 > [693354.106275] do_syscall_64+0x112/0x370 > [693354.106280] entry_SYSCALL_64_after_hwframe+0x65/0xca > > [693354.106329] The buggy address belongs to the object at ffff888be0a35580 > which belongs to the cache kmalloc-1k of size 1024 > [693354.106736] The buggy address is located 228 bytes inside of > 1024-byte region [ffff888be0a35580, ffff888be0a35980) > [693354.107114] The buggy address belongs to the page: > [693354.107273] page:ffffea002f828c00 count:1 mapcount:0 mapping:ffff888107c17080 index:0x0 compound_mapcount: 0 > [693354.107606] flags: 0x17ffffc0008100(slab|head) > [693354.107760] raw: 0017ffffc0008100 ffffea002fcbc808 ffffea0030bd3a08 ffff888107c17080 > [693354.108020] raw: 0000000000000000 00000000001c001c 00000001ffffffff 0000000000000000 > [693354.108278] page dumped because: kasan: bad access detected > > [693354.108511] Memory state around the buggy address: > [693354.108671] ffff888be0a35500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [693354.116396] ffff888be0a35580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [693354.124473] >ffff888be0a35600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [693354.132421] ^ > [693354.140284] ffff888be0a35680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [693354.147912] ffff888be0a35700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [693354.155281] ================================================================== > > Freeing bfqg is protected by queue lock in blkcg_deactivate_policy(), > but getting/using bfqg is protected by blkcg lock in > bfq_io_set_weight_legacy(). If bfq_io_set_weight_legacy() get bfqg > before freeing bfqg and use bfqg in the after, the use-after-free > will occur. > > CPU0 CPU1 > blkcg_deactivate_policy > spin_lock_irq(&q->queue_lock) > bfq_io_set_weight_legacy > spin_lock_irq(&blkcg->lock) > blkg_to_bfqg(blkg) > pd_to_bfqg(blkg->pd[pol->plid]) > ^^^^^^blkg->pd[pol->plid] != NULL > bfqg != NULL > pol->pd_free_fn(blkg->pd[pol->plid]) > pd_to_bfqg(blkg->pd[pol->plid]) > bfqg_put(bfqg) > kfree(bfqg) > blkg->pd[pol->plid] = NULL > spin_unlock_irq(q->queue_lock); > bfq_group_set_weight(bfqg, val, 0) > bfqg->entity.new_weight > ^^^^^^trigger uaf here > spin_unlock_irq(&blkcg->lock); > > To fix this use-after-free, instead of holding blkcg->lock while > walking ->blkg_list and getting/using bfqg, RCU walk ->blkg_list and > hold the blkg's queue lock while getting/using bfqg. > > Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") > Signed-off-by: Li Jinlin <lijinlin3@huawei.com> > --- > block/bfq-cgroup.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c > index e2f14508f2d6..7209060caa90 100644 > --- a/block/bfq-cgroup.c > +++ b/block/bfq-cgroup.c > @@ -1025,21 +1025,25 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, > struct blkcg *blkcg = css_to_blkcg(css); > struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); > struct blkcg_gq *blkg; > + struct bfq_group *bfqg; > int ret = -ERANGE; > > if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) > return ret; > > ret = 0; > - spin_lock_irq(&blkcg->lock); > bfqgd->weight = (unsigned short)val; > - hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { > - struct bfq_group *bfqg = blkg_to_bfqg(blkg); > + > + rcu_read_lock(); > + hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { > + spin_lock_irq(&blkg->q->queue_lock); > + bfqg = blkg_to_bfqg(blkg); > > if (bfqg) > bfq_group_set_weight(bfqg, val, 0); > + spin_unlock_irq(&blkg->q->queue_lock); > } > - spin_unlock_irq(&blkcg->lock); > + rcu_read_unlock(); > > return ret; > } Ping Paolo.
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index e2f14508f2d6..7209060caa90 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -1025,21 +1025,25 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, struct blkcg *blkcg = css_to_blkcg(css); struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); struct blkcg_gq *blkg; + struct bfq_group *bfqg; int ret = -ERANGE; if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) return ret; ret = 0; - spin_lock_irq(&blkcg->lock); bfqgd->weight = (unsigned short)val; - hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { - struct bfq_group *bfqg = blkg_to_bfqg(blkg); + + rcu_read_lock(); + hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { + spin_lock_irq(&blkg->q->queue_lock); + bfqg = blkg_to_bfqg(blkg); if (bfqg) bfq_group_set_weight(bfqg, val, 0); + spin_unlock_irq(&blkg->q->queue_lock); } - spin_unlock_irq(&blkcg->lock); + rcu_read_unlock(); return ret; }