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[94.245.46.61]) by smtp.gmail.com with ESMTPSA id d8sm286841lfa.49.2021.03.18.09.59.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Mar 2021 09:59:09 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 18 Mar 2021 17:59:07 +0100 To: vjitta@codeaurora.org Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, vinmenon@codeaurora.org Subject: Re: [PATCH] mm: vmalloc: Prevent use after free in _vm_unmap_aliases Message-ID: <20210318165907.GA10448@pc638.lan> References: <1616062105-23263-1-git-send-email-vjitta@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1616062105-23263-1-git-send-email-vjitta@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 46EBB5001848 X-Stat-Signature: 93kc59gg796nouf4t6cj5ks9cajgdt4n Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=mail-lj1-f182.google.com; client-ip=209.85.208.182 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616086760-825165 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 18, 2021 at 03:38:25PM +0530, vjitta@codeaurora.org wrote: > From: Vijayanand Jitta > > A potential use after free can occur in _vm_unmap_aliases > where an already freed vmap_area could be accessed, Consider > the following scenario: > > Process 1 Process 2 > > __vm_unmap_aliases __vm_unmap_aliases > purge_fragmented_blocks_allcpus rcu_read_lock() > rcu_read_lock() > list_del_rcu(&vb->free_list) > list_for_each_entry_rcu(vb .. ) > __purge_vmap_area_lazy > kmem_cache_free(va) > va_start = vb->va->va_start Or maybe we should switch to kfree_rcu() instead of kmem_cache_free()? -- Vlad Rezki