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[2.111.15.75]) by smtp.gmail.com with ESMTPSA id d20sm3111879lja.32.2019.05.28.13.48.47 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 May 2019 13:48:47 -0700 (PDT) Subject: Re: [PATCH] trace: Avoid memory leak in predicate_parse() To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, mingo@redhat.com References: <20190528104400.388e4c3f@gandalf.local.home> <20190528154338.29976-1-tomasbortoli@gmail.com> <20190528163104.67763762@gandalf.local.home> From: Tomas Bortoli Openpgp: preference=signencrypt Autocrypt: addr=tomasbortoli@gmail.com; prefer-encrypt=mutual; keydata= mQINBFpCTZMBEADNZ1+Ibh0Z4pgGRcd1aOUMbe/YfHktmajjcoTnKmZZunjoUVAl8waeLITd BC2c8i1wHzHcnthrmb1izs5XlG6PZnl8n5tjysSNbwggzS1NcEK1qgn5VjNlHQ5aRMUwCC51 kicBiNmlQk2UuzzWwdheRGnaf+O1MNhC0GBeEDKQAL5obOU92pzflv6wWNACr+lHxdnpyies mOnRMjH16NjuTkrGbEmJe+MKp0qbjvR3R/dmFC1wczniRMQmV5w3MZ/N9wRappE+Atc1fOM+ wP7AWNuPvrKg4bN5uqKZLDFH7OFpxvjgVdWM40n0cQfqElWY9as+228Sltdd1XyHtUWRF2VW O1l5L0kX0+7+B5k/fpLhXqD3Z7DK7wRXpXmY59pofk7aFdcN97ZK+r6R7mqrwX4W9IpsPhkT kUyg3/Dx/khBZlJKFoUP325/hoH684bSiPEBroel9alB7gTq2ueoFwy6R3q5CMUw3D+CZWHA 3xllu46TRQ/Vt2g0cIHQNPoye2OWYFJ6kSEvaLpymjNDJ9ph2EuHegonDfOaYSq34ic2BcdB JkCgXRLP5K7KtRNJqqR+DM8xByeGmQv9yp6S97el+SiM9R53RhHawJZGz0EPl+2Q6+5mgh3u wXOlkmGrrSrlB8lc567l34ECl6NFtUPIL7H5vppIXAFl7JZUdQARAQABtB50b21hcyA8dG9t YXNib3J0b2xpQGdtYWlsLmNvbT6JAlQEEwEIAD4WIQSKOZIcNF9TdAG6W8ARUi5Y8x1zLgUC WkJNkwIbIwUJCWYBgAULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRARUi5Y8x1zLvCXD/9h iaZWJ6bC6jHHPGDMknFdbpNnB5w1hBivu9KwAm4LyEI+taWhmUg5WUNO1CmDa2WGSUSTk9lo uq7gH8Y7zwGrYOEDVuldjRjPFR/1yW2JdAmbwzcYkVU0ZUhyo2XzgFjsnv3vJGHk/afEopce U6mOc2BsGDpo2izVTE/HVaiLE9jyKQF6Riy04QBRAvxbDvx1rl26GIxVI6coBFf4SZhZOnc0 dzsip0/xaSRRIMG0d75weezIG49qK3IHyw2Fw5pEFY8tP0JJVxtrq2MZw+n4WmW9BVD/oCd/ b0JZ4volQbOFmdLzcAi2w7DMcKVkW11I1fiRZ/vLMvA4b79r6mn3WJ8aMIaodG6CQzmDNcsF br+XVp8rc58m9q69BTzDH0xTStxXiwozyISAe2VGbGUbK9ngU/H1RX0Y01uQ9Dz0KfyjA0/Z QOBa4N1n1qoKFzoxTpu0Vyumkc5EnTk8NdWszt7UAtNSaIZcBuWHR7Kp0DqRHwom0kgTiNXJ 8uNgvvFTkPd2Pdz1BqbpN1Fj856xPuKIiqs5qXI2yh3GhntFDbTOwOU3rr3x5NEv3wFVojdi HcLM+KVf29YkRHzuEQT5YT9h6qTk2aFRqq3HSXrP56hQ3whR7bQtziJspkuj+ekeTxcZ5lr4 9FJI03hQJ4HbHn6x/Xw0+WjIOo4jBeUEI7kCDQRaQk2TARAA4JCPcQcISPAKKC1n9VQxgdH3 oMqxhJ+gh/0Yb394ZYWLf7qOVQf/MgALPQIIFpcwYrw7gK4hsN7kj1vwPFy9JIqZtkgbmJHm aCj1LkZuf8tp5uvqzMZGcgm28IO6qDhPggeUE3hfA/y5++Vt0Jsmrz5zVPY0bOrLh1bItLnF U3uoaHWkAi/rhM6WwlsxemefzKulXoR9PIGVZ/QGjBGsTkNbTpiz2KsN+Ff/ZgjBJzGQNgha kc6a+eXyGC0YE8fRoTQekTi/GqGY7gfRKkgZDPi0Ul0sPZQJo07Dpw0nh5l6sOO+1yXygcoA V7I4bUeANZ9QJzbzZALgtxbT6jTKC0HUbF9iFb0yEkffkQuhhIqud7RkITe25hZePN8Y6Px0 yF4lEVW/Ti91jMSb4mpZiAaIFcdDV0CAtIYHAcK1ZRVz//+72o4gMZlRxowxduMyRs3L5rE0 ZkFQ6aPan+NBtEk1v3RPqnsQwJsonmiEgfbvybyBpP5MzRZnoAxfQ9vyyXoI5ofbl/+l9wv8 mosKNWIjiQsX3KiyaqygtD/yed5diie5nA7eT6IjL92WfgSelhBCL4jV0fL4w8hah2Azu0Jg 1ZtjjgoDObcAKQ5dLJA0IDsgH/X/G+ZMvkPpPIVaS5QWkiv66hixdKte/4iUrN+4waxJLCit 1KGC2xPJ2UUAEQEAAYkCPAQYAQgAJhYhBIo5khw0X1N0AbpbwBFSLljzHXMuBQJaQk2TAhsM BQkJZgGAAAoJEBFSLljzHXMuOb0P/1EnY4Y6LfQ6bmhJQ6epA3fB70hRWCQsuPYLAgPKRoXy kmWH4ljqQDbA55TtIpnod/woR0IDnZcD7E9cyGzM2rHvSLXTkHhgIWacZHZopAUzq4j0lhiJ Wu57freQPU4rzMVGZXBktUsDMsJwp/3Tl2Kjqylh90qIOlB9laUusLIbl4w5J3EscIJzWvdL y1lJLtBmus/t75wN/aIB8l9YBKGuy0L4SAmjhN52pCgP/S+ANEKvdghQco51a4jD2Pv2uYH7 nUU/Y70AmqOHjPR+qZ0hAUw6B+UtWQ+Fl587Qqi2XPUzdA8G2EjGFFPRlnhf2H/gOyAfeVYL NDwDgm9Yzp7Rx0O1QOnQsXTHqk7K38AdSdM2li/I/zegeblInnLi08Gq6mT6RkD6wV9HE5U3 EIU0rDPyJo54MW39wGjfC2+PM5I0xebbxtnuTewRchVVfm7UWgLAy11pV3xM4wMSJOuqVMOz jYpWKYxDTpvsZ0ginUUY993Gb8k/CxjABEMUGVHhQPZ0OzjHIKS6cTzN6ue8bB+CGOLCaQp1 C0NRT5Tn9zpLxtf5nBExFd/zVENY5vAV2ZbKQdemO54O7j6B9DSgVRrm83GCZxbL4d+qTYBF 3tSCWw/6SG1F3q9gR9QrSC2YRjCmhijUVEh6FhZwB58TNZ1sEEttrps8TDa5tUd9 Message-ID: <77f8591e-6230-7341-7bb3-0599c16bea92@gmail.com> Date: Tue, 28 May 2019 22:48:46 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190528163104.67763762@gandalf.local.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/28/19 10:31 PM, Steven Rostedt wrote: > On Tue, 28 May 2019 17:43:38 +0200 > Tomas Bortoli wrote: > >> @@ -578,6 +578,8 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, >> out_free: >> kfree(op_stack); >> kfree(inverts); >> + for (i = 0; prog_stack[i].pred; i++) >> + kfree(prog_stack[i].pred); >> kfree(prog_stack); >> return ERR_PTR(ret); >> } > > I should have caught this, but thanks to the zero day bot, it found it > first: > > kernel/trace/trace_events_filter.c:582:27-31: ERROR: prog_stack is NULL but dereferenced. > > I changed the patch with the following: > > From dfb4a6f2191a80c8b790117d0ff592fd712d3296 Mon Sep 17 00:00:00 2001 > From: Tomas Bortoli > Date: Tue, 28 May 2019 17:43:38 +0200 > Subject: [PATCH] tracing: Avoid memory leak in predicate_parse() > > In case of errors, predicate_parse() goes to the out_free label > to free memory and to return an error code. > > However, predicate_parse() does not free the predicates of the > temporary prog_stack array, thence leaking them. > > Link: http://lkml.kernel.org/r/20190528154338.29976-1-tomasbortoli@gmail.com > > Cc: stable@vger.kernel.org > Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster") > Reported-by: syzbot+6b8e0fb820e570c59e19@syzkaller.appspotmail.com > Signed-off-by: Tomas Bortoli > [ Added protection around freeing prog_stack[i].pred ] > Signed-off-by: Steven Rostedt (VMware) > --- > kernel/trace/trace_events_filter.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c > index d3e59312ef40..5079d1db3754 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -428,7 +428,7 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, > op_stack = kmalloc_array(nr_parens, sizeof(*op_stack), GFP_KERNEL); > if (!op_stack) > return ERR_PTR(-ENOMEM); > - prog_stack = kmalloc_array(nr_preds, sizeof(*prog_stack), GFP_KERNEL); > + prog_stack = kcalloc(nr_preds, sizeof(*prog_stack), GFP_KERNEL); > if (!prog_stack) { > parse_error(pe, -ENOMEM, 0); > goto out_free; > @@ -579,7 +579,11 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, > out_free: > kfree(op_stack); > kfree(inverts); > - kfree(prog_stack); > + if (prog_stack) { > + for (i = 0; prog_stack[i].pred; i++) > + kfree(prog_stack[i].pred); > + kfree(prog_stack); > + } > return ERR_PTR(ret); > } > > Oops again, I should have been more careful. Thanks.