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Fri, 22 Jan 2021 06:20:53 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id c14sm5970461qtp.4.2021.01.22.06.20.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Jan 2021 06:20:52 -0800 (PST) Subject: Re: [PATCH] linux: mips: Fix getdents64 fallback on mips64-n32 To: Florian Weimer , Adhemerval Zanella via Libc-alpha Cc: Florian Weimer , Andreas Schwab References: <20201116211743.2228063-1-adhemerval.zanella@linaro.org> <873619gfo2.fsf@mid.deneb.enyo.de> <08cc387e-e0ec-7242-fdc6-a9b163331986@linaro.org> <87a6t1p24o.fsf@oldenburg.str.redhat.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 Message-ID: Date: Fri, 22 Jan 2021 11:20:50 -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: <87a6t1p24o.fsf@oldenburg.str.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-13.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_ASCII_DIVIDERS, KAM_NUMSUBJECT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Jan 2021 14:20:56 -0000 On 22/01/2021 09:49, Florian Weimer wrote: > * Adhemerval Zanella via Libc-alpha: > >> Would it be more in line of what you have suggested? > > Yes, thanks. >> while ((char *) kdp < (char *) skdp + r) >> { >> + >> + /* Obtain the d_ino, d_off, and d_reclen from kernel filled buffer. */ >> + struct kernel_dirent kdirent; >> + memcpy (&kdirent, kdp, sizeof (struct kernel_dirent)); > > I believe this should use offsetof (struct kernel_dirent, d_name) > for the size of the copy. Technically, the padding at the end of the > struct may not be present in the buffer. Right, I was working the assumption that kernel always returned at least one byte do d_name ('\0'). > >> @@ -118,19 +115,19 @@ __getdents64 (int fd, void *buf, size_t nbytes) >> } >> nb += new_reclen; >> >> + struct dirent64 d64; >> + d64.d_ino = kdirent.d_ino; >> + d64.d_off = kdirent.d_off; >> + d64.d_reclen = new_reclen; >> + d64.d_type = *((char *) kdp + kdirent.d_reclen - 1); >> + memcpy (d64.d_name, kdp->d_name, >> + kdirent.d_reclen - offsetof (struct kernel_dirent, d_name)); >> + >> + memcpy (dp, &d64, new_reclen); >> + last_offset = kdirent.d_off; >> >> dp = (struct dirent64 *) ((char *) dp + new_reclen); >> + kdp = (struct kernel_dirent *) (((char *) kdp) + kdirent.d_reclen); >> } > > I think the first memcpy is wrong: It has to go into the result buffer > because only that will be large enough. 256 bytes for d_name may not be > enough. The second memcpy should only copy the header (before d_name). > Indeed, I fixed on the patch below. The tst-getdents64 does pass on mips64 and mips64-n32 on gccfarm machine (I explicit disabled the getdents64 call for the test). -- [PATCH] linux: mips: Fix getdents64 fallback on mips64-n32 GCC mainline shows the following error: ../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c: In function '__getdents64': ../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:121:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds] 121 | memcpy (((char *) dp + offsetof (struct dirent64, d_ino)), | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 122 | KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino)); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:123:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds] 123 | memcpy (((char *) dp + offsetof (struct dirent64, d_off)), | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 124 | KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off)); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The issue is due both d_ino and d_off fields for mips64-n32 kernel_dirent are 32-bits, while this is using memcpy to copy 64 bits from it into the glibc dirent64. The fix is to use a temporary buffer to read the correct type from kernel_dirent. Checked with a build-many-glibcs.py for mips64el-linux-gnu and I also checked the tst-getdents64 on mips64el 4.1.4 kernel with and without fallback enabled (by manually setting the getdents64_supported). --- .../unix/sysv/linux/mips/mips64/getdents64.c | 37 +++++++++---------- sysdeps/unix/sysv/linux/tst-getdents64.c | 29 ++++++++++++--- 2 files changed, 42 insertions(+), 24 deletions(-) diff --git a/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c b/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c index a218f68104..ed6589ab94 100644 --- a/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c +++ b/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c @@ -90,17 +90,14 @@ __getdents64 (int fd, void *buf, size_t nbytes) while ((char *) kdp < (char *) skdp + r) { - /* This macro is used to avoid aliasing violation. */ -#define KDP_MEMBER(src, member) \ - (__typeof__((struct kernel_dirent){0}.member) *) \ - memcpy (&((__typeof__((struct kernel_dirent){0}.member)){0}), \ - ((char *)(src) + offsetof (struct kernel_dirent, member)),\ - sizeof ((struct kernel_dirent){0}.member)) - /* This is a conservative approximation, since some of size_diff might fit into the existing padding for alignment. */ - unsigned short int k_reclen = *KDP_MEMBER (kdp, d_reclen); - unsigned short int new_reclen = ALIGN_UP (k_reclen + size_diff, + + /* Obtain the d_ino, d_off, and d_reclen from kernel filled buffer. */ + struct kernel_dirent kdirent; + memcpy (&kdirent, kdp, offsetof (struct kernel_dirent, d_name)); + + unsigned short int new_reclen = ALIGN_UP (kdirent.d_reclen + size_diff, _Alignof (struct dirent64)); if (nb + new_reclen > nbytes) { @@ -118,19 +115,21 @@ __getdents64 (int fd, void *buf, size_t nbytes) } nb += new_reclen; - memcpy (((char *) dp + offsetof (struct dirent64, d_ino)), - KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino)); - memcpy (((char *) dp + offsetof (struct dirent64, d_off)), - KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off)); - last_offset = *KDP_MEMBER (kdp, d_off); - memcpy (((char *) dp + offsetof (struct dirent64, d_reclen)), - &new_reclen, sizeof (new_reclen)); - dp->d_type = *((char *) kdp + k_reclen - 1); + struct dirent64 d64; + d64.d_ino = kdirent.d_ino; + d64.d_off = kdirent.d_off; + d64.d_reclen = new_reclen; + d64.d_type = *((char *) kdp + kdirent.d_reclen - 1); + /* First copy only the header. */ + memcpy (dp, &d64, offsetof (struct dirent64, d_name)); + /* And then the d_name. */ memcpy (dp->d_name, kdp->d_name, - k_reclen - offsetof (struct kernel_dirent, d_name)); + kdirent.d_reclen - offsetof (struct kernel_dirent, d_name)); + + last_offset = kdirent.d_off; dp = (struct dirent64 *) ((char *) dp + new_reclen); - kdp = (struct kernel_dirent *) (((char *) kdp) + k_reclen); + kdp = (struct kernel_dirent *) (((char *) kdp) + kdirent.d_reclen); } return (char *) dp - (char *) buf; diff --git a/sysdeps/unix/sysv/linux/tst-getdents64.c b/sysdeps/unix/sysv/linux/tst-getdents64.c index 379ecbbcc6..691444d56e 100644 --- a/sysdeps/unix/sysv/linux/tst-getdents64.c +++ b/sysdeps/unix/sysv/linux/tst-getdents64.c @@ -76,8 +76,18 @@ large_buffer_checks (int fd) } } -static int -do_test (void) +static void +do_test_large_size (void) +{ + int fd = xopen (".", O_RDONLY | O_DIRECTORY, 0); + TEST_VERIFY (fd >= 0); + large_buffer_checks (fd); + + xclose (fd); +} + +static void +do_test_by_size (size_t buffer_size) { /* The test compares the iteration order with readdir64. */ DIR *reference = opendir ("."); @@ -98,7 +108,7 @@ do_test (void) non-existing data. */ struct { - char buffer[1024]; + char buffer[buffer_size]; struct dirent64 pad; } data; @@ -153,10 +163,19 @@ do_test (void) rewinddir (reference); } - large_buffer_checks (fd); - xclose (fd); closedir (reference); +} + +static int +do_test (void) +{ + do_test_by_size (512); + do_test_by_size (1024); + do_test_by_size (4096); + + do_test_large_size (); + return 0; } -- 2.25.1