linux-stable.git/kernel/events, branch v6.18.47

perf: Reject exited events as group leaders

2026-08-23T12:27:07+00:00

[ Upstream commit fa091f46c3833fb22384f10eade2b4e1e1d0b278 ]

perf_event_remove_on_exec() sets remove-on-exec events to the EXIT state
and detaches their group relationships.  The event's file descriptor can
remain open, however, and perf_event_open() currently accepts that event
as a group leader because its early validation rejects only REVOKED and
DEAD events.

A new sibling can consequently be linked to the detached leader.  When
the leader is closed, perf_group_detach() observes that its
PERF_ATTACH_GROUP bit is already clear and skips the new sibling.  The
sibling then retains a group_leader pointer to the freed event.

Reject group leaders in the EXIT state.  Perform the check while holding
the shared context mutex so that an exec in the target task cannot detach
the leader between validation and group attachment.

[peterz: make the earlier test fully consistent]
Fixes: 037a3c43edfb ("perf/core: Detach event groups during remove_on_exec")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Kyle Zeng 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/20260806205655.75722-1-kylebot@openai.com
Signed-off-by: Sasha Levin

perf/core: Fix group leader use-after-free after sibling detach

2026-08-19T16:18:17+00:00

commit 42c5ca1f0a288a52878bd72a5595b08261057438 upstream.

perf_group_detach() handles leader and sibling detach differently. When the
group leader is detached, all siblings are promoted to singleton events and
their group_leader pointer is reset to themselves. When a sibling is
detached, it is removed from the leader's sibling_list, but its
group_leader pointer is left pointing at the old leader.

That is harmless when the sibling is being closed and freed immediately, as
in the DETACH_DEAD path. It is not safe when the sibling is detached but
kept alive, such as during CPU hotplug with DETACH_GROUP. In that case the
sibling is removed from the context, while its file descriptor can still
keep it alive.

A typical failing sequence is:

  - A group contains leader L and sibling S.
  - CPU hot-unplug detaches S with DETACH_GROUP, removing it from
    L->sibling_list but leaving S->group_leader == L.
  - L is later closed and freed.
  - A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and
    dereferences the freed leader.

This was reproduced by running the perf event fuzzer, CPU hotplug, and a
stress workload concurrently:

  Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb
  CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT
  pc : perf_ioctl+0x34c/0xc68
  x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b
  Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)
  Call trace:
  perf_ioctl+0x34c/0xc68 (P)
  __arm64_sys_ioctl+0xa0/0xf4
  invoke_syscall+0x58/0xe4
  el0_svc_common+0xa8/0xdc
  do_el0_svc+0x1c/0x28
  el0_svc+0x40/0xc0
  el0t_64_sync_handler+0x68/0xdc
  el0t_64_sync+0x1c4/0x1c8

The fault happened in perf_ioctl(), where perf_event_for_each() follows
the stale group_leader pointer and perf_event_for_each_child() then
dereferences the freed leader's context.

Fix the use-after-free by promoting the detached sibling to a singleton.
Also fix __event_disable() cgroup accounting and event state change.

Fixes: 8a49542c0554 ("perf_events: Fix races in group composition")
Assisted-by: PatchWise:gpt-5.5
Signed-off-by: Aditya Chillara 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Dapeng Mi 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260807-fix-group-leader-uaf-v3-1-b0c2310c9a0d@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman

uprobes: Fix NULL pointer dereference in hprobe_expire()

2026-08-09T18:25:17+00:00

commit cc679d7a6303e84d769f2afcde1fc51c51f127cd upstream.

Forking a task that has a pending uretprobe can oops the kernel with a
NULL pointer dereference in the clone() path:

  BUG: kernel NULL pointer dereference, address: 0000000000000018
  Oops: 0002 [#1] SMP NOPTI
  RIP: 0010:hprobe_expire
  CR2: 0000000000000018
  Call Trace:
   uprobe_copy_process
   copy_process
   kernel_clone
   __x64_sys_clone
   do_syscall_64
   entry_SYSCALL_64_after_hwframe

This was found on real hosts on Meta fleet.

I've got the impression that this is what is happening:

  CPU 1                          CPU 2 (traced task)
  -----                          -------------------
                                 hit uprobe, prepare_uretprobe():
                                   hprobe LEASED, refcount >= 1
  uprobe_unregister()
    put_uprobe(): refcount -> 0
                                 fork() -> dup_utask()
                                   hprobe_expire(hprobe, true)
                                     try_get_uprobe() -> NULL
                                     get_uprobe(NULL)   <-- Oops

Only take the extra reference when the uprobe is non-NULL; a NULL means
it is gone and is the correct value to return.

Fixes: dd1a7567784e ("uprobes: SRCU-protect uretprobe lifetime (with timeout)")
Signed-off-by: Breno Leitao 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Oleg Nesterov 
Acked-by: Andrii Nakryiko 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260729-uprobe-v1-1-61896b87c867@debian.org
Signed-off-by: Greg Kroah-Hartman

perf/aux: Fix page UAF in map_range()

2026-07-18T14:53:30+00:00

commit 5948aaf64f81f217a25dcc2bf6c0779bca19566c upstream.

map_range() reads rb->aux_pages[], rb->aux_nr_pages and rb->aux_pgoff via
perf_mmap_to_page() while holding only event->mmap_mutex. Those fields are
serialized by rb->aux_mutex, and mmap_mutex is per event.

Thus, two events sharing one rb via PERF_EVENT_IOC_SET_OUTPUT can race
rb_alloc_aux() with map_range(), leading to a page-UAF scenario as follows:

  CPU 0                           CPU 1
  =====                           =====
  rb_alloc_aux()                  map_range()
  [1]: allocate rb->aux_pages[0]
  [2]: rb->aux_nr_pages++
                                  [3]: perf_mmap_to_page()
                                         returns rb->aux_pages[0]
                                  [4]: map it as VM_PFNMAP
  [5]: rb->aux_pgoff = 1

  munmap the page
  [6]: free rb->aux_pages[0]

Pages mapped as VM_PFNMAP have no refcount protection, so CPU 1 holds a
mapping to a freed physical frame.

Fix this by taking rb->aux_mutex across the page walk in map_range().

Fixes: b709eb872e19 ("perf: map pages in advance")
Signed-off-by: Lee Jia Jie 
Signed-off-by: Ingo Molnar 
Cc: stable@vger.kernel.org
Cc: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Namhyung Kim 
Signed-off-by: Greg Kroah-Hartman

perf/core: Detach event groups during remove_on_exec

2026-07-18T14:53:06+00:00

[ Upstream commit 037a3c43edfb597665dd34457cd22b14692f2ba3 ]

perf_event_remove_on_exec() removes events by calling
perf_event_exit_event(). For top-level events, this removes the event from
the context with DETACH_EXIT only.

This can leave inconsistent group state when a removed event is a group
leader and the group contains siblings without remove_on_exec. If the group
was active, the surviving siblings can remain active and attached to the
removed leader's sibling list, but are no longer represented by a valid
group leader on the PMU context active lists.

A later close of the removed leader uses DETACH_GROUP and can promote the
still-active siblings from this stale group state. The next schedule-in can
then add an already-linked active_list entry again, corrupting the PMU
context active list.

With DEBUG_LIST enabled, this is caught as a list_add double-add in
merge_sched_in().

Fix this by detaching group relationships when remove_on_exec removes an
event. This preserves the existing task-exit and revoke behavior, while
ensuring surviving siblings are ungrouped before the removed event leaves
the context.

Fixes: 2e498d0a74e5 ("perf: Add support for event removal on exec")
Signed-off-by: Taeyang Lee <0wn@theori.io>
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/ai65GgZcC0LAlWLG@Taeyangs-MacBook-Pro.local
Signed-off-by: Sasha Levin

perf: Make sure to use pmu_ctx->pmu for groups

2026-04-02T11:22:53+00:00

[ Upstream commit 4b9ce671960627b2505b3f64742544ae9801df97 ]

Oliver reported that x86_pmu_del() ended up doing an out-of-bound memory access
when group_sched_in() fails and needs to roll back.

This *should* be handled by the transaction callbacks, but he found that when
the group leader is a software event, the transaction handlers of the wrong PMU
are used. Despite the move_group case in perf_event_open() and group_sched_in()
using pmu_ctx->pmu.

Turns out, inherit uses event->pmu to clone the events, effectively undoing the
move_group case for all inherited contexts. Fix this by also making inherit use
pmu_ctx->pmu, ensuring all inherited counters end up in the same pmu context.

Similarly, __perf_event_read() should use equally use pmu_ctx->pmu for the
group case.

Fixes: bd2756811766 ("perf: Rewrite core context handling")
Reported-by: Oliver Rosenberg 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Ian Rogers 
Link: https://patch.msgid.link/20260309133713.GB606826@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin

x86/uprobes: Fix XOL allocation failure for 32-bit tasks

2026-03-12T11:09:28+00:00

[ Upstream commit d55c571e4333fac71826e8db3b9753fadfbead6a ]

This script

	#!/usr/bin/bash

	echo 0 > /proc/sys/kernel/randomize_va_space

	echo 'void main(void) {}' > TEST.c

	# -fcf-protection to ensure that the 1st endbr32 insn can't be emulated
	gcc -m32 -fcf-protection=branch TEST.c -o test

	bpftrace -e 'uprobe:./test:main {}' -c ./test

"hangs", the probed ./test task enters an endless loop.

The problem is that with randomize_va_space == 0
get_unmapped_area(TASK_SIZE - PAGE_SIZE) called by xol_add_vma() can not
just return the "addr == TASK_SIZE - PAGE_SIZE" hint, this addr is used
by the stack vma.

arch_get_unmapped_area_topdown() doesn't take TIF_ADDR32 into account and
in_32bit_syscall() is false, this leads to info.high_limit > TASK_SIZE.
vm_unmapped_area() happily returns the high address > TASK_SIZE and then
get_unmapped_area() returns -ENOMEM after the "if (addr > TASK_SIZE - len)"
check.

handle_swbp() doesn't report this failure (probably it should) and silently
restarts the probed insn. Endless loop.

I think that the right fix should change the x86 get_unmapped_area() paths
to rely on TIF_ADDR32 rather than in_32bit_syscall(). Note also that if
CONFIG_X86_X32_ABI=y, in_x32_syscall() falsely returns true in this case
because ->orig_ax = -1.

But we need a simple fix for -stable, so this patch just sets TS_COMPAT if
the probed task is 32-bit to make in_ia32_syscall() true.

Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Reported-by: Paulo Andrade 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/all/aV5uldEvV7pb4RA8@redhat.com/
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/aWO7Fdxn39piQnxu@redhat.com
Signed-off-by: Sasha Levin

perf: Fix __perf_event_overflow() vs perf_remove_from_context() race

2026-03-12T11:09:17+00:00

[ Upstream commit c9bc1753b3cc41d0e01fbca7f035258b5f4db0ae ]

Make sure that __perf_event_overflow() runs with IRQs disabled for all
possible callchains. Specifically the software events can end up running
it with only preemption disabled.

This opens up a race vs perf_event_exit_event() and friends that will go
and free various things the overflow path expects to be present, like
the BPF program.

Fixes: 592903cdcbf6 ("perf_counter: add an event_list")
Reported-by: Simond Hu 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Simond Hu 
Link: https://patch.msgid.link/20260224122909.GV1395416@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin

perf/core: Fix invalid wait context in ctx_sched_in()

2026-03-12T11:09:13+00:00

[ Upstream commit 486ff5ad49bc50315bcaf6d45f04a33ef0a45ced ]

Lockdep found a bug in the event scheduling when a pinned event was
failed and wakes up the threads in the ring buffer like below.

It seems it should not grab a wait-queue lock under perf-context lock.
Let's do it with irq_work.

  [   39.913691] =============================
  [   39.914157] [ BUG: Invalid wait context ]
  [   39.914623] 6.15.0-next-20250530-next-2025053 #1 Not tainted
  [   39.915271] -----------------------------
  [   39.915731] repro/837 is trying to lock:
  [   39.916191] ffff88801acfabd8 (&event->waitq){....}-{3:3}, at: __wake_up+0x26/0x60
  [   39.917182] other info that might help us debug this:
  [   39.917761] context-{5:5}
  [   39.918079] 4 locks held by repro/837:
  [   39.918530]  #0: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: __perf_event_task_sched_in+0xd1/0xbc0
  [   39.919612]  #1: ffff88806ca3c6f8 (&cpuctx_lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1a7/0xbc0
  [   39.920748]  #2: ffff88800d91fc18 (&ctx->lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1f9/0xbc0
  [   39.921819]  #3: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: perf_event_wakeup+0x6c/0x470

Fixes: f4b07fd62d4d ("perf/core: Use POLLHUP for a pinned event in error")
Closes: https://lore.kernel.org/lkml/aD2w50VDvGIH95Pf@ly-workstation
Reported-by: "Lai, Yi" 
Signed-off-by: Namhyung Kim 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: "Lai, Yi" 
Link: https://patch.msgid.link/20250603045105.1731451-1-namhyung@kernel.org
Signed-off-by: Sasha Levin

perf/core: Fix refcount bug and potential UAF in perf_mmap

2026-03-12T11:09:07+00:00

commit 77de62ad3de3967818c3dbe656b7336ebee461d2 upstream.

Syzkaller reported a refcount_t: addition on 0; use-after-free warning
in perf_mmap.

The issue is caused by a race condition between a failing mmap() setup
and a concurrent mmap() on a dependent event (e.g., using output
redirection).

In perf_mmap(), the ring_buffer (rb) is allocated and assigned to
event->rb with the mmap_mutex held. The mutex is then released to
perform map_range().

If map_range() fails, perf_mmap_close() is called to clean up.
However, since the mutex was dropped, another thread attaching to
this event (via inherited events or output redirection) can acquire
the mutex, observe the valid event->rb pointer, and attempt to
increment its reference count. If the cleanup path has already
dropped the reference count to zero, this results in a
use-after-free or refcount saturation warning.

Fix this by extending the scope of mmap_mutex to cover the
map_range() call. This ensures that the ring buffer initialization
and mapping (or cleanup on failure) happens atomically effectively,
preventing other threads from accessing a half-initialized or
dying ring buffer.

Closes: https://lore.kernel.org/oe-kbuild-all/202602020208.m7KIjdzW-lkp@intel.com/
Reported-by: kernel test robot 
Signed-off-by: Haocheng Yu 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/20260202162057.7237-1-yuhaocheng035@gmail.com
Signed-off-by: Greg Kroah-Hartman