From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 04/10] sscanf: fix overflow
Date: Sat, 2 May 2015 03:51:16 +0300 [thread overview]
Message-ID: <20150502005116.GD21655@p183.telecom.by> (raw)
In-Reply-To: <20150502004714.GA21655@p183.telecom.by>
Fun fact:
uint8_t val;
sscanf("256", "%hhu", &val);
will return 1 (as it should), and make val=0 (as it should not).
Apart from correctness, patch allows to remove checks and switch
to proper types in several (most?) cases:
grep -e 'scanf.*%[0-9]\+[dioux]' -n -r .
Such checks can be incorrect too, checking for 3 digits with %3u
for parsing uint8_t is not enough.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
lib/vsprintf.c | 45 ++++++++++++++++++++++++++++++++++-----------
1 file changed, 34 insertions(+), 11 deletions(-)
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2632,44 +2632,67 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
switch (qualifier) {
case 'H': /* that's 'hh' in format */
- if (is_sign)
+ if (is_sign) {
+ if (val.s != (signed char)val.s)
+ goto out;
*va_arg(args, signed char *) = val.s;
- else
+ } else {
+ if (val.u != (unsigned char)val.u)
+ goto out;
*va_arg(args, unsigned char *) = val.u;
+ }
break;
case 'h':
- if (is_sign)
+ if (is_sign) {
+ if (val.s != (short)val.s)
+ goto out;
*va_arg(args, short *) = val.s;
- else
+ } else {
+ if (val.u != (unsigned short)val.u)
+ goto out;
*va_arg(args, unsigned short *) = val.u;
+ }
break;
case 'l':
- if (is_sign)
+ if (is_sign) {
+ if (val.s != (long)val.s)
+ goto out;
*va_arg(args, long *) = val.s;
- else
+ } else {
+ if (val.u != (unsigned long)val.u)
+ goto out;
*va_arg(args, unsigned long *) = val.u;
+ }
break;
case 'L':
- if (is_sign)
+ if (is_sign) {
*va_arg(args, long long *) = val.s;
- else
+ } else {
*va_arg(args, unsigned long long *) = val.u;
+ }
break;
case 'Z':
case 'z':
+ if (val.u != (size_t)val.u)
+ goto out;
*va_arg(args, size_t *) = val.u;
break;
default:
- if (is_sign)
+ if (is_sign) {
+ if (val.s != (int)val.s)
+ goto out;
*va_arg(args, int *) = val.s;
- else
+ } else {
+ if (val.u != (unsigned int)val.u)
+ goto out;
*va_arg(args, unsigned int *) = val.u;
+ }
break;
}
num++;
str += len;
}
-
+out:
return num;
}
EXPORT_SYMBOL(vsscanf);
next prev parent reply other threads:[~2015-05-02 0:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-02 0:47 [PATCH 01/10] Add parse_integer() (replacement for simple_strto*()) Alexey Dobriyan
2015-05-02 0:48 ` [PATCH 02/10] parse_integer: rewrite kstrto*() Alexey Dobriyan
2015-05-02 0:50 ` [PATCH 03/10] parse_integer: convert sscanf() Alexey Dobriyan
2015-05-02 1:10 ` [PATCH CORRECT " Alexey Dobriyan
2015-05-02 0:51 ` Alexey Dobriyan [this message]
2015-05-05 9:51 ` [PATCH 04/10] sscanf: fix overflow Rasmus Villemoes
2015-05-05 11:10 ` Alexey Dobriyan
2015-05-06 7:49 ` Rasmus Villemoes
2015-05-02 0:53 ` [PATCH 05/10] parse_integer: convert lib/ Alexey Dobriyan
2015-05-04 14:10 ` Rasmus Villemoes
2015-05-04 14:57 ` Alexey Dobriyan
2015-05-02 0:55 ` [PATCH 06/10] parse_integer: convert mm/ Alexey Dobriyan
2015-05-04 14:33 ` Rasmus Villemoes
2015-05-04 15:09 ` Alexey Dobriyan
2015-05-02 0:56 ` [PATCH 07/10] parse_integer: convert misc fs/ code Alexey Dobriyan
2015-05-02 0:59 ` [PATCH 08/10] fs/cachefiles/: convert to parse_integer() Alexey Dobriyan
2015-05-02 1:01 ` [PATCH 09/10] ocfs2: convert to parse_integer()/kstrto*() Alexey Dobriyan
2015-05-02 1:03 ` [PATCH 10/10] ext2, ext3, ext4: " Alexey Dobriyan
2015-05-04 13:24 ` [PATCH 01/10] Add parse_integer() (replacement for simple_strto*()) Rasmus Villemoes
2015-05-04 14:32 ` Alexey Dobriyan
2015-05-04 16:44 ` Rasmus Villemoes
2015-05-04 19:54 ` Alexey Dobriyan
2015-05-04 21:48 ` Rasmus Villemoes
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