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Tue, 03 Sep 2024 05:09:06 -0400 X-MC-Unique: UeqO92NEOPeS0Oogj4V-_g-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 81DBA18BC2DE; Tue, 3 Sep 2024 09:09:01 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.38]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 94EDD19560AA; Tue, 3 Sep 2024 09:08:54 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 3 Sep 2024 11:08:51 +0200 (CEST) Date: Tue, 3 Sep 2024 11:08:43 +0200 From: Oleg Nesterov To: Sven Schnelle Cc: Michael Ellerman , Masami Hiramatsu , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , Linus Torvalds , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH] uprobes: use vm_special_mapping close() functionality Message-ID: <20240903090843.GA17936@redhat.com> References: <20240903073629.2442754-1-svens@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240903073629.2442754-1-svens@linux.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On 09/03, Sven Schnelle wrote: > > [ 44.505448] ================================================================== 20:37:27 [3421/145075] > [ 44.505455] BUG: KASAN: slab-use-after-free in special_mapping_close+0x9c/0xc8 > [ 44.505471] Read of size 8 at addr 00000000868dac48 by task sh/1384 > [ 44.505479] > [ 44.505486] CPU: 51 UID: 0 PID: 1384 Comm: sh Not tainted 6.11.0-rc6-next-20240902-dirty #1496 > [ 44.505503] Hardware name: IBM 3931 A01 704 (z/VM 7.3.0) > [ 44.505508] Call Trace: > [ 44.505511] [<000b0324d2f78080>] dump_stack_lvl+0xd0/0x108 > [ 44.505521] [<000b0324d2f5435c>] print_address_description.constprop.0+0x34/0x2e0 > [ 44.505529] [<000b0324d2f5464c>] print_report+0x44/0x138 > [ 44.505536] [<000b0324d1383192>] kasan_report+0xc2/0x140 > [ 44.505543] [<000b0324d2f52904>] special_mapping_close+0x9c/0xc8 ^^^^^^^^^^^^^^^^^^^^^ Caused by [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping https://lore.kernel.org/all/20240812082605.743814-1-mpe@ellerman.id.au/ ? > +static void uprobe_clear_state(const struct vm_special_mapping *sm, struct vm_area_struct *vma) > +{ > + struct xol_area *area = container_of(vma->vm_private_data, struct xol_area, xol_mapping); > + > + mutex_lock(&delayed_uprobe_lock); > + delayed_uprobe_remove(NULL, vma->vm_mm); > + mutex_unlock(&delayed_uprobe_lock); > + > + if (!area) > + return; > + > + put_page(area->pages[0]); > + kfree(area->bitmap); > + kfree(area); > +} > + > static struct xol_area *__create_xol_area(unsigned long vaddr) > { > struct mm_struct *mm = current->mm; > @@ -1481,6 +1500,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) > > area->xol_mapping.name = "[uprobes]"; > area->xol_mapping.fault = NULL; > + area->xol_mapping.close = uprobe_clear_state; LGTM. but with or without this fix __create_xol_area() also needs area->xol_mapping.mremap = NULL; ? And in the longer term I think we should probably add a single instance of "struct vm_special_mapping uprobe_special_mapping with ->fault != NULL but this is another issue. Oleg.