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Tue, 24 Nov 2020 06:14:09 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id l8sm12426360qtj.93.2020.11.24.06.14.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Nov 2020 06:14:09 -0800 (PST) To: Xiaoming Ni , eggert@cs.ucla.edu, libc-alpha@sourceware.org, carlos@redhat.com, glibc-bugs@sourceware.org, drepper.fsp@gmail.com, unassigned@sourceware.org Cc: wangle6@huawei.com References: <20201124131652.111854-1-nixiaoming@huawei.com> From: Adhemerval Zanella Autocrypt: addr=adhemerval.zanella@linaro.org; prefer-encrypt=mutual; keydata= mQINBFcVGkoBEADiQU2x/cBBmAVf5C2d1xgz6zCnlCefbqaflUBw4hB/bEME40QsrVzWZ5Nq 8kxkEczZzAOKkkvv4pRVLlLn/zDtFXhlcvQRJ3yFMGqzBjofucOrmdYkOGo0uCaoJKPT186L NWp53SACXguFJpnw4ODI64ziInzXQs/rUJqrFoVIlrPDmNv/LUv1OVPKz20ETjgfpg8MNwG6 iMizMefCl+RbtXbIEZ3TE/IaDT/jcOirjv96lBKrc/pAL0h/O71Kwbbp43fimW80GhjiaN2y WGByepnkAVP7FyNarhdDpJhoDmUk9yfwNuIuESaCQtfd3vgKKuo6grcKZ8bHy7IXX1XJj2X/ BgRVhVgMHAnDPFIkXtP+SiarkUaLjGzCz7XkUn4XAGDskBNfbizFqYUQCaL2FdbW3DeZqNIa nSzKAZK7Dm9+0VVSRZXP89w71Y7JUV56xL/PlOE+YKKFdEw+gQjQi0e+DZILAtFjJLoCrkEX w4LluMhYX/X8XP6/C3xW0yOZhvHYyn72sV4yJ1uyc/qz3OY32CRy+bwPzAMAkhdwcORA3JPb kPTlimhQqVgvca8m+MQ/JFZ6D+K7QPyvEv7bQ7M+IzFmTkOCwCJ3xqOD6GjX3aphk8Sr0dq3 4Awlf5xFDAG8dn8Uuutb7naGBd/fEv6t8dfkNyzj6yvc4jpVxwARAQABtElBZGhlbWVydmFs IFphbmVsbGEgTmV0dG8gKExpbmFybyBWUE4gS2V5KSA8YWRoZW1lcnZhbC56YW5lbGxhQGxp bmFyby5vcmc+iQI3BBMBCAAhBQJXFRpKAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJ EKqx7BSnlIjv0e8P/1YOYoNkvJ+AJcNUaM5a2SA9oAKjSJ/M/EN4Id5Ow41ZJS4lUA0apSXW NjQg3VeVc2RiHab2LIB4MxdJhaWTuzfLkYnBeoy4u6njYcaoSwf3g9dSsvsl3mhtuzm6aXFH /Qsauav77enJh99tI4T+58rp0EuLhDsQbnBic/ukYNv7sQV8dy9KxA54yLnYUFqH6pfH8Lly sTVAMyi5Fg5O5/hVV+Z0Kpr+ZocC1YFJkTsNLAW5EIYSP9ftniqaVsim7MNmodv/zqK0IyDB GLLH1kjhvb5+6ySGlWbMTomt/or/uvMgulz0bRS+LUyOmlfXDdT+t38VPKBBVwFMarNuREU2 69M3a3jdTfScboDd2ck1u7l+QbaGoHZQ8ZNUrzgObltjohiIsazqkgYDQzXIMrD9H19E+8fw kCNUlXxjEgH/Kg8DlpoYJXSJCX0fjMWfXywL6ZXc2xyG/hbl5hvsLNmqDpLpc1CfKcA0BkK+ k8R57fr91mTCppSwwKJYO9T+8J+o4ho/CJnK/jBy1pWKMYJPvvrpdBCWq3MfzVpXYdahRKHI ypk8m4QlRlbOXWJ3TDd/SKNfSSrWgwRSg7XCjSlR7PNzNFXTULLB34sZhjrN6Q8NQZsZnMNs TX8nlGOVrKolnQPjKCLwCyu8PhllU8OwbSMKskcD1PSkG6h3r0AquQINBFcVGkoBEACgAdbR Ck+fsfOVwT8zowMiL3l9a2DP3Eeak23ifdZG+8Avb/SImpv0UMSbRfnw/N81IWwlbjkjbGTu oT37iZHLRwYUFmA8fZX0wNDNKQUUTjN6XalJmvhdz9l71H3WnE0wneEM5ahu5V1L1utUWTyh VUwzX1lwJeV3vyrNgI1kYOaeuNVvq7npNR6t6XxEpqPsNc6O77I12XELic2+36YibyqlTJIQ V1SZEbIy26AbC2zH9WqaKyGyQnr/IPbTJ2Lv0dM3RaXoVf+CeK7gB2B+w1hZummD21c1Laua +VIMPCUQ+EM8W9EtX+0iJXxI+wsztLT6vltQcm+5Q7tY+HFUucizJkAOAz98YFucwKefbkTp eKvCfCwiM1bGatZEFFKIlvJ2QNMQNiUrqJBlW9nZp/k7pbG3oStOjvawD9ZbP9e0fnlWJIsj 6c7pX354Yi7kxIk/6gREidHLLqEb/otuwt1aoMPg97iUgDV5mlNef77lWE8vxmlY0FBWIXuZ yv0XYxf1WF6dRizwFFbxvUZzIJp3spAao7jLsQj1DbD2s5+S1BW09A0mI/1DjB6EhNN+4bDB SJCOv/ReK3tFJXuj/HbyDrOdoMt8aIFbe7YFLEExHpSk+HgN05Lg5TyTro8oW7TSMTk+8a5M kzaH4UGXTTBDP/g5cfL3RFPl79ubXwARAQABiQIfBBgBCAAJBQJXFRpKAhsMAAoJEKqx7BSn lIjvI/8P/jg0jl4Tbvg3B5kT6PxJOXHYu9OoyaHLcay6Cd+ZrOd1VQQCbOcgLFbf4Yr+rE9l mYsY67AUgq2QKmVVbn9pjvGsEaz8UmfDnz5epUhDxC6yRRvY4hreMXZhPZ1pbMa6A0a/WOSt AgFj5V6Z4dXGTM/lNManr0HjXxbUYv2WfbNt3/07Db9T+GZkpUotC6iknsTA4rJi6u2ls0W9 1UIvW4o01vb4nZRCj4rni0g6eWoQCGoVDk/xFfy7ZliR5B+3Z3EWRJcQskip/QAHjbLa3pml xAZ484fVxgeESOoaeC9TiBIp0NfH8akWOI0HpBCiBD5xaCTvR7ujUWMvhsX2n881r/hNlR9g fcE6q00qHSPAEgGr1bnFv74/1vbKtjeXLCcRKk3Ulw0bY1OoDxWQr86T2fZGJ/HIZuVVBf3+ gaYJF92GXFynHnea14nFFuFgOni0Mi1zDxYH/8yGGBXvo14KWd8JOW0NJPaCDFJkdS5hu0VY 7vJwKcyHJGxsCLU+Et0mryX8qZwqibJIzu7kUJQdQDljbRPDFd/xmGUFCQiQAncSilYOcxNU EMVCXPAQTteqkvA+gNqSaK1NM9tY0eQ4iJpo+aoX8HAcn4sZzt2pfUB9vQMTBJ2d4+m/qO6+ cFTAceXmIoFsN8+gFN3i8Is3u12u8xGudcBPvpoy4OoG Subject: Re: [PATCH v3] io:nftw/ftw:fix stack overflow when large nopenfd [BZ #26353] Message-ID: <81700b7c-429a-9014-68d9-78826bb2946a@linaro.org> Date: Tue, 24 Nov 2020 11:14:05 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201124131652.111854-1-nixiaoming@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-14.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=unavailable autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: glibc-bugs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-bugs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Nov 2020 14:14:12 -0000 On 24/11/2020 10:16, Xiaoming Ni wrote: > In ftw_startup(), call alloca to apply for a large amount of stack space. > When descriptors is very large, stack overflow is triggered. BZ #26353 > > Replace the memory application of data.dirstreams from alloca() to malloc() > by referring to the memory application of data.dirbuf in the current function. > Combine the memory allocation of data.dirbuf and data.dirstreams according > to the advice of Adhemerval Zanella. > > v3: > Combine the memory allocation of data.dirbuf and data.dirstreams > according to the advice of Adhemerval Zanella. > remove the upper limit check of descriptors > v2: https://public-inbox.org/libc-alpha/20200815070851.46403-1-nixiaoming@huawei.com/ > not set errno after malloc fails. > add check ftw return value on testcase > add more testcase > v1: https://public-inbox.org/libc-alpha/20200808084640.49174-1-nixiaoming@huawei.com/ > --- > io/Makefile | 3 ++- > io/ftw.c | 18 ++++++++++-------- > io/tst-bz26353.c | 34 ++++++++++++++++++++++++++++++++++ > 3 files changed, 46 insertions(+), 9 deletions(-) > create mode 100644 io/tst-bz26353.c > > diff --git a/io/Makefile b/io/Makefile > index 6dd2c33fcf..7845d07f45 100644 > --- a/io/Makefile > +++ b/io/Makefile > @@ -68,7 +68,8 @@ tests := test-utime test-stat test-stat2 test-lfs tst-getcwd \ > tst-posix_fallocate tst-posix_fallocate64 \ > tst-fts tst-fts-lfs tst-open-tmpfile \ > tst-copy_file_range tst-getcwd-abspath tst-lockf \ > - tst-ftw-lnk tst-file_change_detection tst-lchmod > + tst-ftw-lnk tst-file_change_detection tst-lchmod \ > + tst-bz26353 > > # Likewise for statx, but we do not need static linking here. > tests-internal += tst-statx > diff --git a/io/ftw.c b/io/ftw.c > index 7104816e85..c38e94dffc 100644 > --- a/io/ftw.c > +++ b/io/ftw.c > @@ -72,6 +72,7 @@ char *alloca (); > #else > # include > #endif > +#include This header is not needed. > > #if ! _LIBC && !HAVE_DECL_STPCPY && !defined stpcpy > char *stpcpy (); > @@ -643,18 +644,19 @@ ftw_startup (const char *dir, int is_nftw, void *func, int descriptors, > __set_errno (ENOENT); > return -1; > } > - Spurious line removal. > data.maxdir = descriptors < 1 ? 1 : descriptors; > data.actdir = 0; > - data.dirstreams = (struct dir_data **) alloca (data.maxdir > - * sizeof (struct dir_data *)); > - memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *)); > - > /* PATH_MAX is always defined when we get here. */ > data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX); > - data.dirbuf = (char *) malloc (data.dirbufsize); > - if (data.dirbuf == NULL) > + data.dirstreams = malloc (data.maxdir * sizeof (struct dir_data *) > + + data.dirbufsize); > + if (data.dirstreams == NULL) > return -1; > + > + memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *)); > + > + data.dirbuf = (char *) data.dirstreams > + + data.maxdir * sizeof (struct dir_data *); > cp = __stpcpy (data.dirbuf, dir); > /* Strip trailing slashes. */ > while (cp > data.dirbuf + 1 && cp[-1] == '/') Ok. > @@ -803,7 +805,7 @@ ftw_startup (const char *dir, int is_nftw, void *func, int descriptors, > out_fail: > save_err = errno; > __tdestroy (data.known_objects, free); > - free (data.dirbuf); > + free (data.dirstreams); > __set_errno (save_err); > > return result; Ok. > diff --git a/io/tst-bz26353.c b/io/tst-bz26353.c > new file mode 100644 > index 0000000000..7567d9c038 > --- /dev/null > +++ b/io/tst-bz26353.c > @@ -0,0 +1,34 @@ It requires a proper Copyright header. > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +int my_func(const char *file, const struct stat *sb ,int flag) > +{ > + printf ("%s\n", file); > + return 0; > +} This does not follow the glibc code style and conventions [1], it also applied to the rest of the file. Also please use the libsupport when creating new tests, check both support/README and support/README-testing.c on how to use it. You might grep the tests include 'support/test-driver.c' to check for more examples. > + > +/*Check whether stack overflow occurs*/ > +int do_test(int large_nopenfd) > +{ > + int ret = ftw("./tst-bz26353", my_func, large_nopenfd); > + printf ("test big num %d, ret=%d errno=%d, without stack overflow\n", > + large_nopenfd, ret, errno); > + return 0; > +} You can check by using a subprocess instead of execve a new one, check support_capture_subprocess on to use libsupport for test it. If you do need to a run a different program, you might use support_capture_subprogram; but I think this test do not really require it. > + > +int main(int argc, char *argv[]) > +{ > + int ret = 0; > + mkdir ("./tst-bz26353", 0755); We have support_create_temp_directory to create temporary directories that are remove on test exit. > + /* The default stack size is 8 MB. > + * Before the bug is fixed, stack overflow will be triggered. */ > + ret += do_test(8192 * 1024); > + ret += do_test(INT_MAX); This test will easily trash a low memory system (it allocate about 16GB on my machine before I killed the process). > + rmdir ("./tst-bz26353"); > + return ret; > +} > [1] https://sourceware.org/glibc/wiki/Style_and_Conventions