| Message ID | 20180410072139.323589-1-yhs@fb.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf,v3] bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog | expand |
On 04/10/2018 09:21 AM, Yonghong Song wrote: > syzbot reported a possible deadlock in perf_event_detach_bpf_prog. > The error details: > ====================================================== > WARNING: possible circular locking dependency detected > 4.16.0-rc7+ #3 Not tainted > ------------------------------------------------------ > syz-executor7/24531 is trying to acquire lock: > (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 > > but task is already holding lock: > (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){++++}: > __might_fault+0x13a/0x1d0 mm/memory.c:4571 > _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 > copy_to_user include/linux/uaccess.h:155 [inline] > bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 > perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 > _perf_ioctl kernel/events/core.c:4750 [inline] > perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 > vfs_ioctl fs/ioctl.c:46 [inline] > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > SYSC_ioctl fs/ioctl.c:701 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > -> #0 (bpf_event_mutex){+.+.}: > lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 > __mutex_lock_common kernel/locking/mutex.c:756 [inline] > __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 > perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 > perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] > _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 > put_event+0x24/0x30 kernel/events/core.c:4204 > perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 > remove_vma+0xb4/0x1b0 mm/mmap.c:172 > remove_vma_list mm/mmap.c:2490 [inline] > do_munmap+0x82a/0xdf0 mm/mmap.c:2731 > mmap_region+0x59e/0x15a0 mm/mmap.c:1646 > do_mmap+0x6c0/0xe00 mm/mmap.c:1483 > do_mmap_pgoff include/linux/mm.h:2223 [inline] > vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 > SYSC_mmap_pgoff mm/mmap.c:1533 [inline] > SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 > SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] > SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 > do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&mm->mmap_sem); > lock(bpf_event_mutex); > lock(&mm->mmap_sem); > lock(bpf_event_mutex); > > *** DEADLOCK *** > ====================================================== > > The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow > user space to query prog array on the same tp") where copy_to_user, > which requires mm->mmap_sem, is called inside bpf_event_mutex lock. > At the same time, during perf_event file descriptor close, > mm->mmap_sem is held first and then subsequent > perf_event_detach_bpf_prog needs bpf_event_mutex lock. > Such a senario caused a deadlock. > > As suggested by Danial, moving copy_to_user out of the Nit: typo :) > bpf_event_mutex lock should fix the problem. > > Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") > Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com > Signed-off-by: Yonghong Song <yhs@fb.com> > --- > include/linux/bpf.h | 4 ++-- > kernel/bpf/core.c | 45 +++++++++++++++++++++++++++++---------------- > kernel/trace/bpf_trace.c | 19 +++++++++++++++---- > 3 files changed, 46 insertions(+), 22 deletions(-) > > Changelog: > v2 -> v3: > . Remove the redundant label in function perf_event_query_prog_array. > v1 -> v2: > . Use the common core function for prog_id copying for two > different prog_array copy routines, suggested by Alexei. > [...] > static void bpf_prog_free_deferred(struct work_struct *work) > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index d88e96d..f505d43 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -977,6 +977,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) > { > struct perf_event_query_bpf __user *uquery = info; > struct perf_event_query_bpf query = {}; > + u32 *ids, prog_cnt, ids_len; > int ret; > > if (!capable(CAP_SYS_ADMIN)) > @@ -985,16 +986,26 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) > return -EINVAL; > if (copy_from_user(&query, uquery, sizeof(query))) > return -EFAULT; > - if (query.ids_len > BPF_TRACE_MAX_PROGS) > + > + ids_len = query.ids_len; > + if (ids_len > BPF_TRACE_MAX_PROGS) > return -E2BIG; > + ids = kcalloc(ids_len, sizeof(u32), GFP_USER | __GFP_NOWARN); > + if (!ids) > + return -ENOMEM; Fix looks good to me, but could you still add a comment stating that we don't need to check for ZERO_SIZE_PTR above since we handle this gracefully in the bpf_prog_array_copy_info() plus it's also required for the case where the user only wants to check for the uquery->prog_cnt, but nothing else. > mutex_lock(&bpf_event_mutex); > ret = bpf_prog_array_copy_info(event->tp_event->prog_array, > - uquery->ids, > - query.ids_len, > - &uquery->prog_cnt); > + ids, > + ids_len, > + &prog_cnt); > mutex_unlock(&bpf_event_mutex); > > + if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) || > + copy_to_user(uquery->ids, ids, ids_len * sizeof(u32))) > + ret = -EFAULT; > + > + kfree(ids); > return ret; > } Thanks, Daniel
On 4/10/18 1:54 AM, Daniel Borkmann wrote: > On 04/10/2018 09:21 AM, Yonghong Song wrote: >> syzbot reported a possible deadlock in perf_event_detach_bpf_prog. >> The error details: >> ====================================================== >> WARNING: possible circular locking dependency detected >> 4.16.0-rc7+ #3 Not tainted >> ------------------------------------------------------ >> syz-executor7/24531 is trying to acquire lock: >> (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 >> >> but task is already holding lock: >> (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 >> >> which lock already depends on the new lock. >> >> the existing dependency chain (in reverse order) is: >> >> -> #1 (&mm->mmap_sem){++++}: >> __might_fault+0x13a/0x1d0 mm/memory.c:4571 >> _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 >> copy_to_user include/linux/uaccess.h:155 [inline] >> bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 >> perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 >> _perf_ioctl kernel/events/core.c:4750 [inline] >> perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 >> vfs_ioctl fs/ioctl.c:46 [inline] >> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 >> SYSC_ioctl fs/ioctl.c:701 [inline] >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 >> do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x42/0xb7 >> >> -> #0 (bpf_event_mutex){+.+.}: >> lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 >> __mutex_lock_common kernel/locking/mutex.c:756 [inline] >> __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 >> mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 >> perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 >> perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] >> _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 >> put_event+0x24/0x30 kernel/events/core.c:4204 >> perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 >> remove_vma+0xb4/0x1b0 mm/mmap.c:172 >> remove_vma_list mm/mmap.c:2490 [inline] >> do_munmap+0x82a/0xdf0 mm/mmap.c:2731 >> mmap_region+0x59e/0x15a0 mm/mmap.c:1646 >> do_mmap+0x6c0/0xe00 mm/mmap.c:1483 >> do_mmap_pgoff include/linux/mm.h:2223 [inline] >> vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 >> SYSC_mmap_pgoff mm/mmap.c:1533 [inline] >> SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 >> SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] >> SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 >> do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x42/0xb7 >> >> other info that might help us debug this: >> >> Possible unsafe locking scenario: >> >> CPU0 CPU1 >> ---- ---- >> lock(&mm->mmap_sem); >> lock(bpf_event_mutex); >> lock(&mm->mmap_sem); >> lock(bpf_event_mutex); >> >> *** DEADLOCK *** >> ====================================================== >> >> The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow >> user space to query prog array on the same tp") where copy_to_user, >> which requires mm->mmap_sem, is called inside bpf_event_mutex lock. >> At the same time, during perf_event file descriptor close, >> mm->mmap_sem is held first and then subsequent >> perf_event_detach_bpf_prog needs bpf_event_mutex lock. >> Such a senario caused a deadlock. >> >> As suggested by Danial, moving copy_to_user out of the > > Nit: typo :) Oh, my bad. will correct. > >> bpf_event_mutex lock should fix the problem. >> >> Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") >> Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com >> Signed-off-by: Yonghong Song <yhs@fb.com> >> --- >> include/linux/bpf.h | 4 ++-- >> kernel/bpf/core.c | 45 +++++++++++++++++++++++++++++---------------- >> kernel/trace/bpf_trace.c | 19 +++++++++++++++---- >> 3 files changed, 46 insertions(+), 22 deletions(-) >> >> Changelog: >> v2 -> v3: >> . Remove the redundant label in function perf_event_query_prog_array. >> v1 -> v2: >> . Use the common core function for prog_id copying for two >> different prog_array copy routines, suggested by Alexei. >> > [...] >> static void bpf_prog_free_deferred(struct work_struct *work) >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c >> index d88e96d..f505d43 100644 >> --- a/kernel/trace/bpf_trace.c >> +++ b/kernel/trace/bpf_trace.c >> @@ -977,6 +977,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) >> { >> struct perf_event_query_bpf __user *uquery = info; >> struct perf_event_query_bpf query = {}; >> + u32 *ids, prog_cnt, ids_len; >> int ret; >> >> if (!capable(CAP_SYS_ADMIN)) >> @@ -985,16 +986,26 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) >> return -EINVAL; >> if (copy_from_user(&query, uquery, sizeof(query))) >> return -EFAULT; >> - if (query.ids_len > BPF_TRACE_MAX_PROGS) >> + >> + ids_len = query.ids_len; >> + if (ids_len > BPF_TRACE_MAX_PROGS) >> return -E2BIG; >> + ids = kcalloc(ids_len, sizeof(u32), GFP_USER | __GFP_NOWARN); >> + if (!ids) >> + return -ENOMEM; > > Fix looks good to me, but could you still add a comment stating that we don't > need to check for ZERO_SIZE_PTR above since we handle this gracefully in the > bpf_prog_array_copy_info() plus it's also required for the case where the user > only wants to check for the uquery->prog_cnt, but nothing else. Will add the comment and send another version. Thanks. > >> mutex_lock(&bpf_event_mutex); >> ret = bpf_prog_array_copy_info(event->tp_event->prog_array, >> - uquery->ids, >> - query.ids_len, >> - &uquery->prog_cnt); >> + ids, >> + ids_len, >> + &prog_cnt); >> mutex_unlock(&bpf_event_mutex); >> >> + if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) || >> + copy_to_user(uquery->ids, ids, ids_len * sizeof(u32))) >> + ret = -EFAULT; >> + >> + kfree(ids); >> return ret; >> } > > Thanks, > Daniel >
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 95a7abd..486e65e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -339,8 +339,8 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs, void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs, struct bpf_prog *old_prog); int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array, - __u32 __user *prog_ids, u32 request_cnt, - __u32 __user *prog_cnt); + u32 *prog_ids, u32 request_cnt, + u32 *prog_cnt); int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, struct bpf_prog *exclude_prog, struct bpf_prog *include_prog, diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index d315b39..ba03ec3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1572,13 +1572,32 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu *progs) return cnt; } +static bool bpf_prog_array_copy_core(struct bpf_prog **prog, + u32 *prog_ids, + u32 request_cnt) +{ + int i = 0; + + for (; *prog; prog++) { + if (*prog == &dummy_bpf_prog.prog) + continue; + prog_ids[i] = (*prog)->aux->id; + if (++i == request_cnt) { + prog++; + break; + } + } + + return !!(*prog); +} + int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs, __u32 __user *prog_ids, u32 cnt) { struct bpf_prog **prog; unsigned long err = 0; - u32 i = 0, *ids; bool nospc; + u32 *ids; /* users of this function are doing: * cnt = bpf_prog_array_length(); @@ -1595,16 +1614,7 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs, return -ENOMEM; rcu_read_lock(); prog = rcu_dereference(progs)->progs; - for (; *prog; prog++) { - if (*prog == &dummy_bpf_prog.prog) - continue; - ids[i] = (*prog)->aux->id; - if (++i == cnt) { - prog++; - break; - } - } - nospc = !!(*prog); + nospc = bpf_prog_array_copy_core(prog, ids, cnt); rcu_read_unlock(); err = copy_to_user(prog_ids, ids, cnt * sizeof(u32)); kfree(ids); @@ -1683,22 +1693,25 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, } int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array, - __u32 __user *prog_ids, u32 request_cnt, - __u32 __user *prog_cnt) + u32 *prog_ids, u32 request_cnt, + u32 *prog_cnt) { + struct bpf_prog **prog; u32 cnt = 0; if (array) cnt = bpf_prog_array_length(array); - if (copy_to_user(prog_cnt, &cnt, sizeof(cnt))) - return -EFAULT; + *prog_cnt = cnt; /* return early if user requested only program count or nothing to copy */ if (!request_cnt || !cnt) return 0; - return bpf_prog_array_copy_to_user(array, prog_ids, request_cnt); + /* this function is called under trace/bpf_trace.c: bpf_event_mutex */ + prog = rcu_dereference_check(array, 1)->progs; + return bpf_prog_array_copy_core(prog, prog_ids, request_cnt) ? -ENOSPC + : 0; } static void bpf_prog_free_deferred(struct work_struct *work) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d88e96d..f505d43 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -977,6 +977,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) { struct perf_event_query_bpf __user *uquery = info; struct perf_event_query_bpf query = {}; + u32 *ids, prog_cnt, ids_len; int ret; if (!capable(CAP_SYS_ADMIN)) @@ -985,16 +986,26 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) return -EINVAL; if (copy_from_user(&query, uquery, sizeof(query))) return -EFAULT; - if (query.ids_len > BPF_TRACE_MAX_PROGS) + + ids_len = query.ids_len; + if (ids_len > BPF_TRACE_MAX_PROGS) return -E2BIG; + ids = kcalloc(ids_len, sizeof(u32), GFP_USER | __GFP_NOWARN); + if (!ids) + return -ENOMEM; mutex_lock(&bpf_event_mutex); ret = bpf_prog_array_copy_info(event->tp_event->prog_array, - uquery->ids, - query.ids_len, - &uquery->prog_cnt); + ids, + ids_len, + &prog_cnt); mutex_unlock(&bpf_event_mutex); + if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) || + copy_to_user(uquery->ids, ids, ids_len * sizeof(u32))) + ret = -EFAULT; + + kfree(ids); return ret; }
syzbot reported a possible deadlock in perf_event_detach_bpf_prog. The error details: ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc7+ #3 Not tainted ------------------------------------------------------ syz-executor7/24531 is trying to acquire lock: (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 but task is already holding lock: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 _perf_ioctl kernel/events/core.c:4750 [inline] perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (bpf_event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 put_event+0x24/0x30 kernel/events/core.c:4204 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 remove_vma+0xb4/0x1b0 mm/mmap.c:172 remove_vma_list mm/mmap.c:2490 [inline] do_munmap+0x82a/0xdf0 mm/mmap.c:2731 mmap_region+0x59e/0x15a0 mm/mmap.c:1646 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(bpf_event_mutex); lock(&mm->mmap_sem); lock(bpf_event_mutex); *** DEADLOCK *** ====================================================== The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") where copy_to_user, which requires mm->mmap_sem, is called inside bpf_event_mutex lock. At the same time, during perf_event file descriptor close, mm->mmap_sem is held first and then subsequent perf_event_detach_bpf_prog needs bpf_event_mutex lock. Such a senario caused a deadlock. As suggested by Danial, moving copy_to_user out of the bpf_event_mutex lock should fix the problem. Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com Signed-off-by: Yonghong Song <yhs@fb.com> --- include/linux/bpf.h | 4 ++-- kernel/bpf/core.c | 45 +++++++++++++++++++++++++++++---------------- kernel/trace/bpf_trace.c | 19 +++++++++++++++---- 3 files changed, 46 insertions(+), 22 deletions(-) Changelog: v2 -> v3: . Remove the redundant label in function perf_event_query_prog_array. v1 -> v2: . Use the common core function for prog_id copying for two different prog_array copy routines, suggested by Alexei.