Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753862AbdGPOUM (ORCPT ); Sun, 16 Jul 2017 10:20:12 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44374 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753437AbdGPORv (ORCPT ); Sun, 16 Jul 2017 10:17:51 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, linux-metag@vger.kernel.org, "Al Viro" , "James Hogan" Date: Sun, 16 Jul 2017 14:56:46 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 131/178] metag/usercopy: Zero rest of buffer from copy_from_user In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7110 Lines: 230 3.16.46-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan commit 563ddc1076109f2b3f88e6d355eab7b6fd4662cb upstream. Currently we try to zero the destination for a failed read from userland in fixup code in the usercopy.c macros. The rest of the destination buffer is then zeroed from __copy_user_zeroing(), which is used for both copy_from_user() and __copy_from_user(). Unfortunately we fail to zero in the fixup code as D1Ar1 is set to 0 before the fixup code entry labels, and __copy_from_user() shouldn't even be zeroing the rest of the buffer. Move the zeroing out into copy_from_user() and rename __copy_user_zeroing() to raw_copy_from_user() since it no longer does any zeroing. This also conveniently matches the name needed for RAW_COPY_USER support in a later patch. Fixes: 373cd784d0fc ("metag: Memory handling") Reported-by: Al Viro Signed-off-by: James Hogan Cc: linux-metag@vger.kernel.org Signed-off-by: Ben Hutchings --- arch/metag/include/asm/uaccess.h | 15 ++++++----- arch/metag/lib/usercopy.c | 57 +++++++++++++--------------------------- 2 files changed, 26 insertions(+), 46 deletions(-) --- a/arch/metag/include/asm/uaccess.h +++ b/arch/metag/include/asm/uaccess.h @@ -192,20 +192,21 @@ extern long __must_check strnlen_user(co #define strlen_user(str) strnlen_user(str, 32767) -extern unsigned long __must_check __copy_user_zeroing(void *to, - const void __user *from, - unsigned long n); +extern unsigned long raw_copy_from_user(void *to, const void __user *from, + unsigned long n); static inline unsigned long copy_from_user(void *to, const void __user *from, unsigned long n) { + unsigned long res = n; if (likely(access_ok(VERIFY_READ, from, n))) - return __copy_user_zeroing(to, from, n); - memset(to, 0, n); - return n; + res = raw_copy_from_user(to, from, n); + if (unlikely(res)) + memset(to + (n - res), 0, res); + return res; } -#define __copy_from_user(to, from, n) __copy_user_zeroing(to, from, n) +#define __copy_from_user(to, from, n) raw_copy_from_user(to, from, n) #define __copy_from_user_inatomic __copy_from_user extern unsigned long __must_check __copy_user(void __user *to, --- a/arch/metag/lib/usercopy.c +++ b/arch/metag/lib/usercopy.c @@ -29,7 +29,6 @@ COPY \ "1:\n" \ " .section .fixup,\"ax\"\n" \ - " MOV D1Ar1,#0\n" \ FIXUP \ " MOVT D1Ar1,#HI(1b)\n" \ " JUMP D1Ar1,#LO(1b)\n" \ @@ -637,16 +636,14 @@ EXPORT_SYMBOL(__copy_user); __asm_copy_user_cont(to, from, ret, \ " GETB D1Ar1,[%1++]\n" \ "2: SETB [%0++],D1Ar1\n", \ - "3: ADD %2,%2,#1\n" \ - " SETB [%0++],D1Ar1\n", \ + "3: ADD %2,%2,#1\n", \ " .long 2b,3b\n") #define __asm_copy_from_user_2x_cont(to, from, ret, COPY, FIXUP, TENTRY) \ __asm_copy_user_cont(to, from, ret, \ " GETW D1Ar1,[%1++]\n" \ "2: SETW [%0++],D1Ar1\n" COPY, \ - "3: ADD %2,%2,#2\n" \ - " SETW [%0++],D1Ar1\n" FIXUP, \ + "3: ADD %2,%2,#2\n" FIXUP, \ " .long 2b,3b\n" TENTRY) #define __asm_copy_from_user_2(to, from, ret) \ @@ -656,32 +653,26 @@ EXPORT_SYMBOL(__copy_user); __asm_copy_from_user_2x_cont(to, from, ret, \ " GETB D1Ar1,[%1++]\n" \ "4: SETB [%0++],D1Ar1\n", \ - "5: ADD %2,%2,#1\n" \ - " SETB [%0++],D1Ar1\n", \ + "5: ADD %2,%2,#1\n", \ " .long 4b,5b\n") #define __asm_copy_from_user_4x_cont(to, from, ret, COPY, FIXUP, TENTRY) \ __asm_copy_user_cont(to, from, ret, \ " GETD D1Ar1,[%1++]\n" \ "2: SETD [%0++],D1Ar1\n" COPY, \ - "3: ADD %2,%2,#4\n" \ - " SETD [%0++],D1Ar1\n" FIXUP, \ + "3: ADD %2,%2,#4\n" FIXUP, \ " .long 2b,3b\n" TENTRY) #define __asm_copy_from_user_4(to, from, ret) \ __asm_copy_from_user_4x_cont(to, from, ret, "", "", "") - #define __asm_copy_from_user_8x64(to, from, ret) \ asm volatile ( \ " GETL D0Ar2,D1Ar1,[%1++]\n" \ "2: SETL [%0++],D0Ar2,D1Ar1\n" \ "1:\n" \ " .section .fixup,\"ax\"\n" \ - " MOV D1Ar1,#0\n" \ - " MOV D0Ar2,#0\n" \ "3: ADD %2,%2,#8\n" \ - " SETL [%0++],D0Ar2,D1Ar1\n" \ " MOVT D0Ar2,#HI(1b)\n" \ " JUMP D0Ar2,#LO(1b)\n" \ " .previous\n" \ @@ -721,11 +712,12 @@ EXPORT_SYMBOL(__copy_user); "SUB %1, %1, #4\n") -/* Copy from user to kernel, zeroing the bytes that were inaccessible in - userland. The return-value is the number of bytes that were - inaccessible. */ -unsigned long __copy_user_zeroing(void *pdst, const void __user *psrc, - unsigned long n) +/* + * Copy from user to kernel. The return-value is the number of bytes that were + * inaccessible. + */ +unsigned long raw_copy_from_user(void *pdst, const void __user *psrc, + unsigned long n) { register char *dst asm ("A0.2") = pdst; register const char __user *src asm ("A1.2") = psrc; @@ -738,7 +730,7 @@ unsigned long __copy_user_zeroing(void * __asm_copy_from_user_1(dst, src, retn); n--; if (retn) - goto copy_exception_bytes; + return retn + n; } if ((unsigned long) dst & 1) { /* Worst case - byte copy */ @@ -746,14 +738,14 @@ unsigned long __copy_user_zeroing(void * __asm_copy_from_user_1(dst, src, retn); n--; if (retn) - goto copy_exception_bytes; + return retn + n; } } if (((unsigned long) src & 2) && n >= 2) { __asm_copy_from_user_2(dst, src, retn); n -= 2; if (retn) - goto copy_exception_bytes; + return retn + n; } if ((unsigned long) dst & 2) { /* Second worst case - word copy */ @@ -761,7 +753,7 @@ unsigned long __copy_user_zeroing(void * __asm_copy_from_user_2(dst, src, retn); n -= 2; if (retn) - goto copy_exception_bytes; + return retn + n; } } @@ -777,7 +769,7 @@ unsigned long __copy_user_zeroing(void * __asm_copy_from_user_8x64(dst, src, retn); n -= 8; if (retn) - goto copy_exception_bytes; + return retn + n; } } @@ -793,7 +785,7 @@ unsigned long __copy_user_zeroing(void * __asm_copy_from_user_8x64(dst, src, retn); n -= 8; if (retn) - goto copy_exception_bytes; + return retn + n; } } #endif @@ -803,7 +795,7 @@ unsigned long __copy_user_zeroing(void * n -= 4; if (retn) - goto copy_exception_bytes; + return retn + n; } /* If we get here, there were no memory read faults. */ @@ -829,21 +821,8 @@ unsigned long __copy_user_zeroing(void * /* If we get here, retn correctly reflects the number of failing bytes. */ return retn; - - copy_exception_bytes: - /* We already have "retn" bytes cleared, and need to clear the - remaining "n" bytes. A non-optimized simple byte-for-byte in-line - memset is preferred here, since this isn't speed-critical code and - we'd rather have this a leaf-function than calling memset. */ - { - char *endp; - for (endp = dst + n; dst < endp; dst++) - *dst = 0; - } - - return retn + n; } -EXPORT_SYMBOL(__copy_user_zeroing); +EXPORT_SYMBOL(raw_copy_from_user); #define __asm_clear_8x64(to, ret) \ asm volatile ( \