From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk
Subject: [PATCH 06/12] scanf: fix type range overflow
Date: Fri, 8 May 2015 21:34:32 +0300 [thread overview]
Message-ID: <20150508183432.GD9182@p183.telecom.by> (raw)
In-Reply-To: <20150508182911.GA9044@p183.telecom.by>
Fun fact:
uint8_t val;
sscanf("256", "%hhu", &val);
will return 1 and make val=0 (clearly bogus).
Userspace sscanf() reports 1 parsed value, returns incorrect value
but sets errno to ERANGE only for "%u" conversion and higher.
%hhu and %hu are left in the cold.
Having no way to report errno=ERANGE in kernel, don't report
successful parsing.
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(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 6509c54..58051b4 100644
--- 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);
--
2.0.4
next prev parent reply other threads:[~2015-05-08 18:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-08 18:29 [PATCH 01/12] kstrto*: accept "-0" for signed conversion Alexey Dobriyan
2015-05-08 18:30 ` [PATCH 02/12] Add parse_integer() (replacement for simple_strto*()) Alexey Dobriyan
2015-05-08 20:46 ` Andrew Morton
2015-05-08 21:52 ` Rasmus Villemoes
2015-05-10 13:52 ` Alexey Dobriyan
2015-05-13 12:19 ` Alexey Dobriyan
2015-05-10 15:52 ` Noel Grandin
2015-07-09 19:28 ` Andrew Morton
2015-07-10 6:46 ` Alexey Dobriyan
2015-05-08 18:31 ` [PATCH 03/12] parse_integer: add runtime testsuite Alexey Dobriyan
2015-05-08 18:33 ` [PATCH 04/12] parse-integer: rewrite kstrto*() Alexey Dobriyan
2015-05-08 18:33 ` [PATCH 05/12] parse_integer: convert scanf() Alexey Dobriyan
2015-05-08 18:34 ` Alexey Dobriyan [this message]
2015-05-08 18:35 ` [PATCH 07/12] parse_integer: convert lib/ Alexey Dobriyan
2015-05-08 18:35 ` [PATCH 08/12] parse_integer: convert mm/ Alexey Dobriyan
2015-05-08 18:36 ` [PATCH 09/12] parse_integer: convert fs/ Alexey Dobriyan
2015-05-08 18:37 ` [PATCH 10/37] parse_integer: convert fs/cachefiles/ Alexey Dobriyan
2015-05-08 18:39 ` [PATCH 11/12] parse_integer: convert ext2, ext3, ext4 Alexey Dobriyan
2015-05-08 18:40 ` [PATCH 12/12] parse_integer: convert fs/ocfs2/ Alexey Dobriyan
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