From patchwork Wed Feb 3 16:50:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Fitzgerald X-Patchwork-Id: 375654 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15D2CC433DB for ; Wed, 3 Feb 2021 16:51:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9FB864F7E for ; Wed, 3 Feb 2021 16:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229606AbhBCQvu (ORCPT ); Wed, 3 Feb 2021 11:51:50 -0500 Received: from mx0a-001ae601.pphosted.com ([67.231.149.25]:27778 "EHLO mx0b-001ae601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S230058AbhBCQva (ORCPT ); Wed, 3 Feb 2021 11:51:30 -0500 Received: from pps.filterd (m0077473.ppops.net [127.0.0.1]) by mx0a-001ae601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 113GfaGj001351; Wed, 3 Feb 2021 10:50:14 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cirrus.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=PODMain02222019; bh=a0GtlEzxAlNvRH9Uj1ARUYn5ueqmy5bgUZPc1jBPbMs=; b=e3UE2/z0ew/N4h5dfmuyUk/pzEjmKVezzisqH2VUascyV/I5W3e3htGy7mxCIzRPzpjM myRHQ44TVedsWOWAt2Rh3vAGJY4rOhUkambnOSHIukXsNBpzHbIUgUTIb/4g7Snk8l5j tY/8f8urBj9ROXCv5jbRMgAd8PsWZLj/vKRgAsdsxNEf11fal8ylmOmh12vMLD33XlA0 Nkbn3IYg3STOH0ENvSr5Ysodrw45ruWZZu7X0RDrgcteQuRAzdrmjFBjqwfMK4WBm9vO PGp7h35y4jXE+P4MzChVFOUwnNpEFkc8qrdKWPtBxsvsqKS67cIvI9iTfQo16ErPy9ds Zw== Received: from ediex02.ad.cirrus.com ([87.246.76.36]) by mx0a-001ae601.pphosted.com with ESMTP id 36d5r6dfr1-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Wed, 03 Feb 2021 10:50:14 -0600 Received: from EDIEX01.ad.cirrus.com (198.61.84.80) by EDIEX02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Wed, 3 Feb 2021 16:50:12 +0000 Received: from ediswmail.ad.cirrus.com (198.61.86.93) by EDIEX01.ad.cirrus.com (198.61.84.80) with Microsoft SMTP Server id 15.1.1913.5 via Frontend Transport; Wed, 3 Feb 2021 16:50:12 +0000 Received: from AUSNPC0LSNW1-debian.cirrus.com (AUSNPC0LSNW1.ad.cirrus.com [198.61.64.44]) by ediswmail.ad.cirrus.com (Postfix) with ESMTP id 2A39311CC; Wed, 3 Feb 2021 16:50:12 +0000 (UTC) From: Richard Fitzgerald To: , , , , , CC: , , , Richard Fitzgerald Subject: [PATCH v4 2/4] lib: vsprintf: Fix handling of number field widths in vsscanf Date: Wed, 3 Feb 2021 16:50:07 +0000 Message-ID: <20210203165009.6299-2-rf@opensource.cirrus.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210203165009.6299-1-rf@opensource.cirrus.com> References: <20210203165009.6299-1-rf@opensource.cirrus.com> MIME-Version: 1.0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 suspectscore=0 bulkscore=0 impostorscore=0 clxscore=1015 mlxlogscore=999 malwarescore=0 adultscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102030100 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The existing code attempted to handle numbers by doing a strto[u]l(), ignoring the field width, and then repeatedly dividing to extract the field out of the full converted value. If the string contains a run of valid digits longer than will fit in a long or long long, this would overflow and no amount of dividing can recover the correct value. This patch fixes vsscanf to obey number field widths when parsing the number. A new _parse_integer_limit() is added that takes a limit for the number of characters to parse. The number field conversion in vsscanf is changed to use this new function. If a number starts with a radix prefix, the field width must be long enough for at last one digit after the prefix. If not, it will be handled like this: sscanf("0x4", "%1i", &i): i=0, scanning continues with the 'x' sscanf("0x4", "%2i", &i): i=0, scanning continues with the '4' This is consistent with the observed behaviour of userland sscanf. Note that this patch does NOT fix the problem of a single field value overflowing the target type. So for example: sscanf("123456789abcdef", "%x", &i); Will not produce the correct result because the value obviously overflows INT_MAX. But sscanf will report a successful conversion. Signed-off-by: Richard Fitzgerald Reviewed-by: Petr Mladek --- lib/kstrtox.c | 13 ++++++-- lib/kstrtox.h | 2 ++ lib/vsprintf.c | 88 +++++++++++++++++++++++++++++--------------------- 3 files changed, 64 insertions(+), 39 deletions(-) diff --git a/lib/kstrtox.c b/lib/kstrtox.c index a118b0b1e9b2..e6d14945df4f 100644 --- a/lib/kstrtox.c +++ b/lib/kstrtox.c @@ -39,20 +39,22 @@ const char *_parse_integer_fixup_radix(const char *s, unsigned int *base) /* * Convert non-negative integer string representation in explicitly given radix - * to an integer. + * to an integer. A maximum of max_chars characters will be converted. + * * Return number of characters consumed maybe or-ed with overflow bit. * If overflow occurs, result integer (incorrect) is still returned. * * Don't you dare use this function. */ -unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p) +unsigned int _parse_integer_limit(const char *s, unsigned int base, + unsigned long long *p, size_t max_chars) { unsigned long long res; unsigned int rv; res = 0; rv = 0; - while (1) { + for (; max_chars > 0; max_chars--) { unsigned int c = *s; unsigned int lc = c | 0x20; /* don't tolower() this line */ unsigned int val; @@ -82,6 +84,11 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long return rv; } +unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p) +{ + return _parse_integer_limit(s, base, p, INT_MAX); +} + static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res) { unsigned long long _res; diff --git a/lib/kstrtox.h b/lib/kstrtox.h index 3b4637bcd254..4c6536f85cac 100644 --- a/lib/kstrtox.h +++ b/lib/kstrtox.h @@ -4,6 +4,8 @@ #define KSTRTOX_OVERFLOW (1U << 31) const char *_parse_integer_fixup_radix(const char *s, unsigned int *base); +unsigned int _parse_integer_limit(const char *s, unsigned int base, + unsigned long long *res, size_t max_chars); unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *res); #endif diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 28bb26cd1f67..6afc47575331 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -53,29 +53,47 @@ #include #include "kstrtox.h" -/** - * simple_strtoull - convert a string to an unsigned long long - * @cp: The start of the string - * @endp: A pointer to the end of the parsed string will be placed here - * @base: The number base to use - * - * This function has caveats. Please use kstrtoull instead. - */ -unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) +static unsigned long long simple_strntoull(const char *startp, size_t max_chars, + char **endp, unsigned int base) { - unsigned long long result; + const char *cp; + unsigned long long result = 0ULL; unsigned int rv; - cp = _parse_integer_fixup_radix(cp, &base); - rv = _parse_integer(cp, base, &result); + if (max_chars == 0) { + cp = startp; + goto out; + } + + cp = _parse_integer_fixup_radix(startp, &base); + if ((cp - startp) >= max_chars) { + cp = startp + max_chars; + goto out; + } + + max_chars -= (cp - startp); + rv = _parse_integer_limit(cp, base, &result, max_chars); /* FIXME */ cp += (rv & ~KSTRTOX_OVERFLOW); - +out: if (endp) *endp = (char *)cp; return result; } + +/** + * simple_strtoull - convert a string to an unsigned long long + * @cp: The start of the string + * @endp: A pointer to the end of the parsed string will be placed here + * @base: The number base to use + * + * This function has caveats. Please use kstrtoull instead. + */ +unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) +{ + return simple_strntoull(cp, UINT_MAX, endp, base); +} EXPORT_SYMBOL(simple_strtoull); /** @@ -88,7 +106,7 @@ EXPORT_SYMBOL(simple_strtoull); */ unsigned long simple_strtoul(const char *cp, char **endp, unsigned int base) { - return simple_strtoull(cp, endp, base); + return simple_strntoull(cp, UINT_MAX, endp, base); } EXPORT_SYMBOL(simple_strtoul); @@ -109,6 +127,19 @@ long simple_strtol(const char *cp, char **endp, unsigned int base) } EXPORT_SYMBOL(simple_strtol); +static long long simple_strntoll(const char *cp, size_t max_chars, char **endp, + unsigned int base) +{ + /* + * simple_strntoull safely handles receiving max_chars==0 in the + * case we start with max_chars==1 and find a '-' prefix. + */ + if (*cp == '-' && max_chars > 0) + return -simple_strntoull(cp + 1, max_chars - 1, endp, base); + + return simple_strntoull(cp, max_chars, endp, base); +} + /** * simple_strtoll - convert a string to a signed long long * @cp: The start of the string @@ -119,10 +150,7 @@ EXPORT_SYMBOL(simple_strtol); */ long long simple_strtoll(const char *cp, char **endp, unsigned int base) { - if (*cp == '-') - return -simple_strtoull(cp + 1, endp, base); - - return simple_strtoull(cp, endp, base); + return simple_strntoll(cp, UINT_MAX, endp, base); } EXPORT_SYMBOL(simple_strtoll); @@ -3449,25 +3477,13 @@ int vsscanf(const char *buf, const char *fmt, va_list args) break; if (is_sign) - val.s = qualifier != 'L' ? - simple_strtol(str, &next, base) : - simple_strtoll(str, &next, base); + val.s = simple_strntoll(str, + field_width > 0 ? field_width : UINT_MAX, + &next, base); else - val.u = qualifier != 'L' ? - simple_strtoul(str, &next, base) : - simple_strtoull(str, &next, base); - - if (field_width > 0 && next - str > field_width) { - if (base == 0) - _parse_integer_fixup_radix(str, &base); - while (next - str > field_width) { - if (is_sign) - val.s = div_s64(val.s, base); - else - val.u = div_u64(val.u, base); - --next; - } - } + val.u = simple_strntoull(str, + field_width > 0 ? field_width : UINT_MAX, + &next, base); switch (qualifier) { case 'H': /* that's 'hh' in format */