linux-stable.git/kernel/events, branch v6.1.185

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

2026-08-27T12:29:02+00:00

[ Upstream commit 42c5ca1f0a288a52878bd72a5595b08261057438 ]

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
[ adjusted `event_sched_out()` calls to the older three-argument form taking `cpuctx` and kept the existing `event->pending_disable = 1;` in the DETACH_DEAD path ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

perf: Fix dangling cgroup pointer in cpuctx

2026-08-27T12:29:02+00:00

[ Upstream commit 3b7a34aebbdf2a4b7295205bf0c654294283ec82 ]

Commit a3c3c6667("perf/core: Fix child_total_time_enabled accounting
bug at task exit") moves the event->state update to before
list_del_event(). This makes the event->state test in list_del_event()
always false; never calling perf_cgroup_event_disable().

As a result, cpuctx->cgrp won't be cleared properly; causing havoc.

Fixes: a3c3c6667("perf/core: Fix child_total_time_enabled accounting bug at task exit")
Signed-off-by: Yeoreum Yun 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: David Wang <00107082@163.com>
Link: https://lore.kernel.org/all/aD2TspKH%2F7yvfYoO@e129823.arm.com/
Stable-dep-of: 42c5ca1f0a28 ("perf/core: Fix group leader use-after-free after sibling detach")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

perf: Fix cgroup state vs ERROR

2026-08-27T12:29:02+00:00

[ Upstream commit 61988e36dc5457cdff7ae7927e8d9ad1419ee998 ]

While chasing down a missing perf_cgroup_event_disable() elsewhere,
Leo Yan found that both perf_put_aux_event() and
perf_remove_sibling_event() were also missing one.

Specifically, the rule is that events that switch to OFF,ERROR need to
call perf_cgroup_event_disable().

Unify the disable paths to ensure this.

Fixes: ab43762ef010 ("perf: Allow normal events to output AUX data")
Fixes: 9f0c4fa111dc ("perf/core: Add a new PERF_EV_CAP_SIBLING event capability")
Reported-by: Leo Yan 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20250605123343.GD35970@noisy.programming.kicks-ass.net
Stable-dep-of: 42c5ca1f0a28 ("perf/core: Fix group leader use-after-free after sibling detach")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix child_total_time_enabled accounting bug at task exit

2026-08-27T12:29:02+00:00

[ Upstream commit a3c3c66670cee11eb13aa43905904bf29cb92d32 ]

The perf events code fails to account for total_time_enabled of
inactive events.

Here is a failure case for accounting total_time_enabled for
CPU PMU events:

  sudo ./perf stat -vvv -e armv8_pmuv3_0/event=0x08/ -e armv8_pmuv3_1/event=0x08/ -- stress-ng --pthread=2 -t 2s
  ...

  armv8_pmuv3_0/event=0x08/: 1138698008 2289429840 2174835740
  armv8_pmuv3_1/event=0x08/: 1826791390 1950025700 847648440
                             `          `          `
                             `          `          > total_time_running with child
                             `          > total_time_enabled with child
                             > count with child

  Performance counter stats for 'stress-ng --pthread=2 -t 2s':

       1,138,698,008      armv8_pmuv3_0/event=0x08/                                               (94.99%)
       1,826,791,390      armv8_pmuv3_1/event=0x08/                                               (43.47%)

The two events above are opened on two different CPU PMUs, for example,
each event is opened for a cluster in an Arm big.LITTLE system, they
will never run on the same CPU.  In theory, the total enabled time should
be same for both events, as two events are opened and closed together.

As the result show, the two events' total enabled time including
child event is different (2289429840 vs 1950025700).

This is because child events are not accounted properly
if a event is INACTIVE state when the task exits:

  perf_event_exit_event()
   `> perf_remove_from_context()
     `> __perf_remove_from_context()
       `> perf_child_detach()   -> Accumulate child_total_time_enabled
         `> list_del_event()    -> Update child event's time

The problem is the time accumulation happens prior to child event's
time updating. Thus, it misses to account the last period's time when
the event exits.

The perf core layer follows the rule that timekeeping is tied to state
change. To address the issue, make __perf_remove_from_context()
handle the task exit case by passing 'DETACH_EXIT' to it and
invoke perf_event_state() for state alongside with accounting the time.

Then, perf_child_detach() populates the time into the parent's time metrics.

After this patch, the bug is fixed:

  sudo ./perf stat -vvv -e armv8_pmuv3_0/event=0x08/ -e armv8_pmuv3_1/event=0x08/ -- stress-ng --pthread=2 -t 10s
  ...
  armv8_pmuv3_0/event=0x08/: 15396770398 32157963940 21898169000
  armv8_pmuv3_1/event=0x08/: 22428964974 32157963940 10259794940

   Performance counter stats for 'stress-ng --pthread=2 -t 10s':

      15,396,770,398      armv8_pmuv3_0/event=0x08/                                               (68.10%)
      22,428,964,974      armv8_pmuv3_1/event=0x08/                                               (31.90%)

[ mingo: Clarified the changelog. ]

Fixes: ef54c1a476aef ("perf: Rework perf_event_exit_event()")
Suggested-by: Peter Zijlstra 
Signed-off-by: Yeoreum Yun 
Signed-off-by: Ingo Molnar 
Tested-by: Leo Yan 
Link: https://lore.kernel.org/r/20250326082003.1630986-1-yeoreum.yun@arm.com
Stable-dep-of: 42c5ca1f0a28 ("perf/core: Fix group leader use-after-free after sibling detach")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

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

2026-03-25T10:03:19+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: Greg Kroah-Hartman

perf: Fix __perf_event_overflow() vs perf_remove_from_context() race

2026-03-25T10:02:54+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

uprobe: Do not emulate/sstep original instruction when ip is changed

2025-12-06T21:12:17+00:00

[ Upstream commit 4363264111e1297fa37aa39b0598faa19298ecca ]

If uprobe handler changes instruction pointer we still execute single
step) or emulate the original instruction and increment the (new) ip
with its length.

This makes the new instruction pointer bogus and application will
likely crash on illegal instruction execution.

If user decided to take execution elsewhere, it makes little sense
to execute the original instruction, so let's skip it.

Acked-by: Oleg Nesterov 
Acked-by: Andrii Nakryiko 
Signed-off-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20250916215301.664963-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

perf: Have get_perf_callchain() return NULL if crosstask and user are set

2025-12-06T21:12:09+00:00

[ Upstream commit 153f9e74dec230f2e070e16fa061bc7adfd2c450 ]

get_perf_callchain() doesn't support cross-task unwinding for user space
stacks, have it return NULL if both the crosstask and user arguments are
set.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20250820180428.426423415@kernel.org
Signed-off-by: Sasha Levin

perf/core: Prevent VMA split of buffer mappings

2025-08-15T10:05:11+00:00

commit b024d7b56c77191cde544f838debb7f8451cd0d6 upstream.

The perf mmap code is careful about mmap()'ing the user page with the
ringbuffer and additionally the auxiliary buffer, when the event supports
it. Once the first mapping is established, subsequent mapping have to use
the same offset and the same size in both cases. The reference counting for
the ringbuffer and the auxiliary buffer depends on this being correct.

Though perf does not prevent that a related mapping is split via mmap(2),
munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls,
which take reference counts, but then the subsequent perf_mmap_close()
calls are not longer fulfilling the offset and size checks. This leads to
reference count leaks.

As perf already has the requirement for subsequent mappings to match the
initial mapping, the obvious consequence is that VMA splits, caused by
resizing of a mapping or partial unmapping, have to be prevented.

Implement the vm_operations_struct::may_split() callback and return
unconditionally -EINVAL.

That ensures that the mapping offsets and sizes cannot be changed after the
fact. Remapping to a different fixed address with the same size is still
possible as it takes the references for the new mapping and drops those of
the old mapping.

Fixes: 45bfb2e50471 ("perf/core: Add AUX area to ring buffer for raw data streams")
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-27504
Signed-off-by: Thomas Gleixner 
Reviewed-by: Lorenzo Stoakes 
Acked-by: Arnaldo Carvalho de Melo 
Acked-by: Vlastimil Babka 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

perf/core: Exit early on perf_mmap() fail

2025-08-15T10:05:11+00:00

commit 07091aade394f690e7b655578140ef84d0e8d7b0 upstream.

When perf_mmap() fails to allocate a buffer, it still invokes the
event_mapped() callback of the related event. On X86 this might increase
the perf_rdpmc_allowed reference counter. But nothing undoes this as
perf_mmap_close() is never called in this case, which causes another
reference count leak.

Return early on failure to prevent that.

Fixes: 1e0fb9ec679c ("perf/core: Add pmu callbacks to track event mapping and unmapping")
Signed-off-by: Thomas Gleixner 
Reviewed-by: Lorenzo Stoakes Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman