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charset="utf-8" sscanf() and friends currently ignore integer overflow, but this is a bad idea. It is much better to detect integer overflow errors and consider this a conversion failure. This implements Linus's suggestion of using '!' to treat integer overflow as wrapping. It does _not_ allow wrapping of unsigned conversions by default, though, as in at least some cases accepting negative numbers is _not_ intended. Suggested-By: Linus Torvalds Signed-off-by: Demi Marie Obenour --- .../hive_isp_css_include/platform_support.h | 1 - include/linux/limits.h | 1 + include/linux/mfd/wl1273-core.h | 3 - include/vdso/limits.h | 3 + lib/vsprintf.c | 82 ++++++++++++++----- 5 files changed, 67 insertions(+), 23 deletions(-) diff --git a/drivers/staging/media/atomisp/pci/hive_isp_css_include/platfor= m_support.h b/drivers/staging/media/atomisp/pci/hive_isp_css_include/platfo= rm_support.h index 0cdef4a5e8b1bed9884133f1a0b9d853d59d43a4..e29b96d8bebf14839f6dd48fdc6= c0f8b029ef31d 100644 --- a/drivers/staging/media/atomisp/pci/hive_isp_css_include/platform_suppo= rt.h +++ b/drivers/staging/media/atomisp/pci/hive_isp_css_include/platform_suppo= rt.h @@ -27,7 +27,6 @@ =20 #define UINT16_MAX USHRT_MAX #define UINT32_MAX UINT_MAX -#define UCHAR_MAX (255) =20 #define CSS_ALIGN(d, a) d __attribute__((aligned(a))) =20 diff --git a/include/linux/limits.h b/include/linux/limits.h index f6bcc936901071f496e3e85bb6e1d93905b12e32..8f7fd85b41fb46e6992d9e5912d= a00424119227a 100644 --- a/include/linux/limits.h +++ b/include/linux/limits.h @@ -8,6 +8,7 @@ =20 #define SIZE_MAX (~(size_t)0) #define SSIZE_MAX ((ssize_t)(SIZE_MAX >> 1)) +#define SSIZE_MIN (-SSIZE_MAX - 1) #define PHYS_ADDR_MAX (~(phys_addr_t)0) =20 #define U8_MAX ((u8)~0U) diff --git a/include/linux/mfd/wl1273-core.h b/include/linux/mfd/wl1273-cor= e.h index c28cf76d5c31ee1c94a9319a2e2d318bf00283a6..b81a229135ed9f756c749122a83= 41816031c8311 100644 --- a/include/linux/mfd/wl1273-core.h +++ b/include/linux/mfd/wl1273-core.h @@ -204,9 +204,6 @@ WL1273_IS2_TRI_OPT | \ WL1273_IS2_RATE_48K) =20 -#define SCHAR_MIN (-128) -#define SCHAR_MAX 127 - #define WL1273_FR_EVENT BIT(0) #define WL1273_BL_EVENT BIT(1) #define WL1273_RDS_EVENT BIT(2) diff --git a/include/vdso/limits.h b/include/vdso/limits.h index 0197888ad0e00b2f853d3f25ffa764f61cca7385..0cad0a2490e5efc194d874025eb= 3e3b846a5c7b4 100644 --- a/include/vdso/limits.h +++ b/include/vdso/limits.h @@ -2,6 +2,9 @@ #ifndef __VDSO_LIMITS_H #define __VDSO_LIMITS_H =20 +#define UCHAR_MAX ((unsigned char)~0U) +#define SCHAR_MAX ((signed char)(UCHAR_MAX >> 1)) +#define SCHAR_MIN ((signed char)(-SCHAR_MAX - 1)) #define USHRT_MAX ((unsigned short)~0U) #define SHRT_MAX ((short)(USHRT_MAX >> 1)) #define SHRT_MIN ((short)(-SHRT_MAX - 1)) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 40f560959b169b4c4ac6154d658cfe76cfd0c5a6..8caccdcda0a2b470cda70c9b383= 7de37207eb512 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -59,7 +59,7 @@ bool no_hash_pointers __ro_after_init; EXPORT_SYMBOL_GPL(no_hash_pointers); =20 -static noinline unsigned long long simple_strntoull(const char *startp, si= ze_t max_chars, char **endp, unsigned int base) +static noinline unsigned long long simple_strntoull(const char *startp, si= ze_t max_chars, char **endp, unsigned int base, bool *overflow) { const char *cp; unsigned long long result =3D 0ULL; @@ -71,6 +71,8 @@ static noinline unsigned long long simple_strntoull(const= char *startp, size_t m if (prefix_chars < max_chars) { rv =3D _parse_integer_limit(cp, base, &result, max_chars - prefix_chars); /* FIXME */ + if (overflow) + *overflow =3D !!(rv & KSTRTOX_OVERFLOW); cp +=3D (rv & ~KSTRTOX_OVERFLOW); } else { /* Field too short for prefix + digit, skip over without converting */ @@ -94,7 +96,7 @@ static noinline unsigned long long simple_strntoull(const= char *startp, size_t m noinline unsigned long long simple_strtoull(const char *cp, char **endp, unsigned i= nt base) { - return simple_strntoull(cp, INT_MAX, endp, base); + return simple_strntoull(cp, INT_MAX, endp, base, NULL); } EXPORT_SYMBOL(simple_strtoull); =20 @@ -130,18 +132,22 @@ long simple_strtol(const char *cp, char **endp, unsig= ned int base) EXPORT_SYMBOL(simple_strtol); =20 static long long simple_strntoll(const char *cp, size_t max_chars, char **= endp, - unsigned int base) + unsigned int base, bool *overflow) { + unsigned long long minand; + bool negate; + /* * simple_strntoull() safely handles receiving max_chars=3D=3D0 in the * case cp[0] =3D=3D '-' && max_chars =3D=3D 1. * If max_chars =3D=3D 0 we can drop through and pass it to simple_strnto= ull() * and the content of *cp is irrelevant. */ - if (*cp =3D=3D '-' && max_chars > 0) - return -simple_strntoull(cp + 1, max_chars - 1, endp, base); - - return simple_strntoull(cp, max_chars, endp, base); + negate =3D *cp =3D=3D '-' && max_chars > 0; + minand =3D simple_strntoull(cp + negate, max_chars - negate, endp, base, = overflow); + if (minand > (unsigned long long)LONG_MAX + negate) + *overflow =3D true; + return negate ? -minand : minand; } =20 /** @@ -3441,7 +3447,7 @@ int vsscanf(const char *buf, const char *fmt, va_list= args) unsigned long long u; } val; s16 field_width; - bool is_sign; + bool is_sign, overflow, allow_overflow; =20 while (*fmt) { /* skip any white space in format */ @@ -3464,6 +3470,9 @@ int vsscanf(const char *buf, const char *fmt, va_list= args) break; ++fmt; =20 + allow_overflow =3D *fmt =3D=3D '!'; + fmt +=3D (int)allow_overflow; + /* skip this conversion. * advance both strings to next white space */ @@ -3649,45 +3658,80 @@ int vsscanf(const char *buf, const char *fmt, va_li= st args) if (is_sign) val.s =3D simple_strntoll(str, field_width >=3D 0 ? field_width : INT_MAX, - &next, base); + &next, base, &overflow); else val.u =3D simple_strntoull(str, field_width >=3D 0 ? field_width : INT_MAX, - &next, base); + &next, base, &overflow); + if (unlikely(overflow && !allow_overflow)) + break; =20 switch (qualifier) { case 'H': /* that's 'hh' in format */ - if (is_sign) + if (is_sign) { + if (unlikely(val.s < SCHAR_MIN || val.s > SCHAR_MAX) && + !allow_overflow) + return num; *va_arg(args, signed char *) =3D val.s; - else + } else { + if (unlikely(val.u > UCHAR_MAX) && !allow_overflow) + return num; *va_arg(args, unsigned char *) =3D val.u; + } break; case 'h': - if (is_sign) + if (is_sign) { + if (unlikely(val.s < SHRT_MIN || val.s > SHRT_MAX) && + !allow_overflow) + return num; *va_arg(args, short *) =3D val.s; - else + } else { + if (unlikely(val.u > USHRT_MAX) && !allow_overflow) + return num; *va_arg(args, unsigned short *) =3D val.u; + } break; case 'l': - if (is_sign) + if (is_sign) { + if (unlikely(val.s < LONG_MIN || val.s > LONG_MAX) && + !allow_overflow) + return num; *va_arg(args, long *) =3D val.s; - else + } else { + if (unlikely(val.u > ULONG_MAX) && !allow_overflow) + return num; *va_arg(args, unsigned long *) =3D val.u; + } break; case 'L': + /* No overflow check needed */ if (is_sign) *va_arg(args, long long *) =3D val.s; else *va_arg(args, unsigned long long *) =3D val.u; break; case 'z': - *va_arg(args, size_t *) =3D val.u; + if (is_sign) { + if (unlikely(val.s < SSIZE_MIN || val.s > SSIZE_MAX)) + return num; + *va_arg(args, ssize_t *) =3D val.s; + } else { + if (unlikely(val.u > SIZE_MAX) && !allow_overflow) + return num; + *va_arg(args, size_t *) =3D val.u; + } break; default: - if (is_sign) + if (is_sign) { + if (unlikely(val.s < INT_MIN || val.s > INT_MAX) && + !allow_overflow) + return num; *va_arg(args, int *) =3D val.s; - else + } else { + if (unlikely(val.u > UINT_MAX) && !allow_overflow) + return num; *va_arg(args, unsigned int *) =3D val.u; + } break; } num++; --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab From nobody Sat Feb 7 19:45:25 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1686416918478745.5995793814224; 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charset="utf-8" Passing spaces before e.g. an integer is usually not intended. This was suggested by Christoph in https://lore.kernel.org/lkml/ZIQrohcizoj4bZWx@infradead.org/. Suggested-by: Christoph Hellwig Signed-off-by: Demi Marie Obenour --- lib/vsprintf.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 8caccdcda0a2b470cda70c9b3837de37207eb512..d2d795d1aff0fd5cc50fb65ffb0= 67067ab9f0dc6 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -3547,8 +3547,6 @@ int vsscanf(const char *buf, const char *fmt, va_list= args) char *s =3D (char *)va_arg(args, char *); if (field_width =3D=3D -1) field_width =3D SHRT_MAX; - /* first, skip leading white space in buffer */ - str =3D skip_spaces(str); =20 /* now copy until next white space */ while (*str && !isspace(*str) && field_width--) @@ -3635,11 +3633,7 @@ int vsscanf(const char *buf, const char *fmt, va_lis= t args) return num; } =20 - /* have some sort of integer conversion. - * first, skip white space in buffer. - */ - str =3D skip_spaces(str); - + /* have some sort of integer conversion. */ digit =3D *str; if (is_sign && digit =3D=3D '-') { if (field_width =3D=3D 1) --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab From nobody Sat Feb 7 19:45:25 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; 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charset="utf-8" This rejects bogus xenstore node values that include e.g. leading spaces or overflow the expected integer type. Signed-off-by: Demi Marie Obenour --- drivers/xen/xenbus/xenbus_xs.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c index 12e02eb01f5991b31db451cc57037205359b347f..7cb2a22a7698ac40c81add23476= 594d9f27de8d0 100644 --- a/drivers/xen/xenbus/xenbus_xs.c +++ b/drivers/xen/xenbus/xenbus_xs.c @@ -569,16 +569,20 @@ int xenbus_scanf(struct xenbus_transaction t, const char *dir, const char *node, const char *fmt, ...) { va_list ap; - int ret; + int ret =3D 0; + unsigned int len; char *val; =20 - val =3D xenbus_read(t, dir, node, NULL); + val =3D xenbus_read(t, dir, node, &len); if (IS_ERR(val)) return PTR_ERR(val); + if (strlen(val) !=3D len) + goto bad; =20 va_start(ap, fmt); ret =3D vsscanf(val, fmt, ap); va_end(ap); +bad: kfree(val); /* Distinctive errno. */ if (ret =3D=3D 0) @@ -636,15 +640,18 @@ int xenbus_gather(struct xenbus_transaction t, const = char *dir, ...) while (ret =3D=3D 0 && (name =3D va_arg(ap, char *)) !=3D NULL) { const char *fmt =3D va_arg(ap, char *); void *result =3D va_arg(ap, void *); + unsigned len; char *p; =20 - p =3D xenbus_read(t, dir, name, NULL); + p =3D xenbus_read(t, dir, name, &len); if (IS_ERR(p)) { ret =3D PTR_ERR(p); break; } - if (fmt) { - if (sscanf(p, fmt, result) =3D=3D 0) + if (strlen(p) !=3D len) + ret =3D -EINVAL; + else if (fmt) { + if (sscanf(p, fmt, result) <=3D 0) ret =3D -EINVAL; kfree(p); } else --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab