From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andrii Nakryiko <andrii@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Jiri Olsa <jolsa@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Paulo Andrade <pandrade@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [BUG] x86: 32-bit uprobes are broken
Date: Wed, 7 Jan 2026 16:52:27 +0100 [thread overview]
Message-ID: <aV6BO4joxggeUut4@redhat.com> (raw)
In-Reply-To: <20260107152716.GG2393663@noisy.programming.kicks-ass.net>
On 01/07, Peter Zijlstra wrote:
>
> On Wed, Jan 07, 2026 at 03:32:53PM +0100, Oleg Nesterov wrote:
> > This patch
> >
> > --- a/kernel/events/uprobes.c
> > +++ b/kernel/events/uprobes.c
> > @@ -1710,8 +1710,11 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
> >
> > if (!area->vaddr) {
> > /* Try to map as high as possible, this is only a hint. */
> > + if (test_thread_flag(TIF_ADDR32))
> > + current_thread_info()->status |= TS_COMPAT;
> > area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
> > PAGE_SIZE, 0, 0);
> > + current_thread_info()->status &= ~TS_COMPAT;
> > if (IS_ERR_VALUE(area->vaddr)) {
> > ret = area->vaddr;
> > goto fail;
>
> Urgh. Also I'm a little bit confused; set_personality_ia32(), which is
> what sets TIF_ADDR32 (afaict) would also set TS_COMPAT, no?
Yep. But TS_COMPAT is per syscall, not per task. It is cleared in
arch_exit_to_user_mode_prepare(), in this case after sys_execve() syscall.
Oleg.
next prev parent reply other threads:[~2026-01-07 15:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-07 14:32 [BUG] x86: 32-bit uprobes are broken Oleg Nesterov
2026-01-07 15:27 ` Peter Zijlstra
2026-01-07 15:52 ` Oleg Nesterov [this message]
2026-01-10 15:37 ` Oleg Nesterov
2026-01-11 15:00 ` [PATCH] x86/uprobes: Fix XOL allocation failure for 32-bit tasks Oleg Nesterov
2026-01-12 16:40 ` Peter Zijlstra
2026-01-12 17:40 ` Oleg Nesterov
2026-01-14 13:10 ` Oleg Nesterov
2026-01-15 21:43 ` [tip: perf/core] " tip-bot2 for Oleg Nesterov
2026-01-16 10:00 ` Oleg Nesterov
2026-01-16 10:41 ` Peter Zijlstra
2026-01-16 10:49 ` tip-bot2 for Oleg Nesterov
2026-01-16 15:27 ` tip-bot2 for Oleg Nesterov
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