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Message-ID: <67f18513.050a0220.0a13.0247.GAE@google.com>
Date: Sat, 05 Apr 2025 12:31:31 -0700
From: syzbot <syzbot+ff3aa851d46ab82953a3@...kaller.appspotmail.com>
To: gshahrouzi@...il.com
Cc: gshahrouzi@...il.com, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com
Subject: Re: #syz test: perf/core: Prevent WARN_ON(!ctx) in __free_event for
partial init failure
> Move the get_ctx(child_ctx) call and the child_event->ctx assignment
> to occur immediately after the child event is allocated via
> perf_event_alloc(). This ensures that child_event->ctx is always
> non-NULL before any subsequent error path within inherit_event calls
> free_event(), satisfying the assumptions of the cleanup code.
>
> Reported-by: syzbot+ff3aa851d46ab82953a3@...kaller.appspotmail.com
> Signed-off-by: Gabriel Shahrouzi <gshahrouzi@...il.com>
> ---
> kernel/events/core.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 0bb21659e252..153ba622cfa0 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -14016,6 +14016,9 @@ inherit_event(struct perf_event *parent_event,
> if (IS_ERR(child_event))
> return child_event;
>
> + get_ctx(child_ctx);
> + child_event->ctx = child_ctx;
> +
> pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
> if (IS_ERR(pmu_ctx)) {
> free_event(child_event);
> @@ -14037,8 +14040,6 @@ inherit_event(struct perf_event *parent_event,
> return NULL;
> }
>
> - get_ctx(child_ctx);
> -
> /*
> * Make the child state follow the state of the parent event,
> * not its attr.disabled bit. We hold the parent's mutex,
> @@ -14059,7 +14060,6 @@ inherit_event(struct perf_event *parent_event,
> local64_set(&hwc->period_left, sample_period);
> }
>
> - child_event->ctx = child_ctx;
> child_event->overflow_handler = parent_event->overflow_handler;
> child_event->overflow_handler_context
> = parent_event->overflow_handler_context;
> --
> 2.43.0
>
want either no args or 2 args (repo, branch), got 9
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