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Message-ID: <2551923b-8c92-4ae7-90ec-2482c9e546e3@kadam.mountain>
Date: Sat, 10 Jun 2023 22:59:17 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Demi Marie Obenour <demi@...isiblethingslab.com>
Cc: Hans de Goede <hdegoede@...hat.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Lee Jones <lee@...nel.org>, Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
linux-media@...r.kernel.org, linux-staging@...ts.linux.dev,
linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 1/3] vsscanf(): Integer overflow is a conversion
failure
On Sat, Jun 10, 2023 at 01:07:41PM -0400, Demi Marie Obenour wrote:
> ---
> .../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/platform_support.h b/drivers/staging/media/atomisp/pci/hive_isp_css_include/platform_support.h
> index 0cdef4a5e8b1bed9884133f1a0b9d853d59d43a4..e29b96d8bebf14839f6dd48fdc6c0f8b029ef31d 100644
> --- a/drivers/staging/media/atomisp/pci/hive_isp_css_include/platform_support.h
> +++ b/drivers/staging/media/atomisp/pci/hive_isp_css_include/platform_support.h
> @@ -27,7 +27,6 @@
>
> #define UINT16_MAX USHRT_MAX
> #define UINT32_MAX UINT_MAX
> -#define UCHAR_MAX (255)
>
> #define CSS_ALIGN(d, a) d __attribute__((aligned(a)))
>
> diff --git a/include/linux/limits.h b/include/linux/limits.h
> index f6bcc936901071f496e3e85bb6e1d93905b12e32..8f7fd85b41fb46e6992d9e5912da00424119227a 100644
> --- a/include/linux/limits.h
> +++ b/include/linux/limits.h
> @@ -8,6 +8,7 @@
>
> #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)
>
> #define U8_MAX ((u8)~0U)
> diff --git a/include/linux/mfd/wl1273-core.h b/include/linux/mfd/wl1273-core.h
> index c28cf76d5c31ee1c94a9319a2e2d318bf00283a6..b81a229135ed9f756c749122a8341816031c8311 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)
>
> -#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..0cad0a2490e5efc194d874025eb3e3b846a5c7b4 100644
> --- a/include/vdso/limits.h
> +++ b/include/vdso/limits.h
> @@ -2,6 +2,9 @@
> #ifndef __VDSO_LIMITS_H
> #define __VDSO_LIMITS_H
>
> +#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))
It looks like you're going to have to redo these patches anyway for
various reasons. Could you pull the U/SCHAR_MAX changes out into a
separate patch?
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 40f560959b169b4c4ac6154d658cfe76cfd0c5a6..8caccdcda0a2b470cda70c9b3837de37207eb512 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);
>
> -static noinline unsigned long long simple_strntoull(const char *startp, size_t max_chars, char **endp, unsigned int base)
> +static noinline unsigned long long simple_strntoull(const char *startp, size_t max_chars, char **endp, unsigned int base, bool *overflow)
> {
> const char *cp;
> unsigned long long result = 0ULL;
> @@ -71,6 +71,8 @@ static noinline unsigned long long simple_strntoull(const char *startp, size_t m
> if (prefix_chars < max_chars) {
> rv = _parse_integer_limit(cp, base, &result, max_chars - prefix_chars);
> /* FIXME */
It's not clear what this FIXME is for, but probably it should go next to
the cp += (rv & ~KSTRTOX_OVERFLOW); line? Does anyone know what it
means? Maybe just delete it.
> + if (overflow)
> + *overflow = !!(rv & KSTRTOX_OVERFLOW);
> cp += (rv & ~KSTRTOX_OVERFLOW);
> } else {
*overflow isn't initialized on the else path.
> /* 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 int base)
> {
> - return simple_strntoull(cp, INT_MAX, endp, base);
> + return simple_strntoull(cp, INT_MAX, endp, base, NULL);
> }
> EXPORT_SYMBOL(simple_strtoull);
>
> @@ -130,18 +132,22 @@ 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)
> + unsigned int base, bool *overflow)
> {
> + unsigned long long minand;
> + bool negate;
> +
> /*
> * simple_strntoull() safely handles receiving max_chars==0 in the
> * case cp[0] == '-' && max_chars == 1.
> * If max_chars == 0 we can drop through and pass it to simple_strntoull()
> * and the content of *cp is irrelevant.
> */
> - if (*cp == '-' && max_chars > 0)
> - return -simple_strntoull(cp + 1, max_chars - 1, endp, base);
> -
> - return simple_strntoull(cp, max_chars, endp, base);
> + negate = *cp == '-' && max_chars > 0;
> + minand = simple_strntoull(cp + negate, max_chars - negate, endp, base, overflow);
> + if (minand > (unsigned long long)LONG_MAX + negate)
> + *overflow = true;
> + return negate ? -minand : minand;
> }
>
> /**
> @@ -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;
>
> 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;
>
> + allow_overflow = *fmt == '!';
> + fmt += (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_list args)
> if (is_sign)
> val.s = simple_strntoll(str,
> field_width >= 0 ? field_width : INT_MAX,
> - &next, base);
> + &next, base, &overflow);
> else
> val.u = simple_strntoull(str,
> field_width >= 0 ? field_width : INT_MAX,
> - &next, base);
> + &next, base, &overflow);
> + if (unlikely(overflow && !allow_overflow))
So that means that *overflow can be uninitialized here.
> + break;
>
> switch (qualifier) {
regards,
dan carpenter
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