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authorJan Beulich <JBeulich@suse.com>2012-10-04 17:13:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-06 03:04:58 +0900
commitda99075c1d368315e1508b6143226c0d27b621e0 (patch)
tree1ceefd8dc83bcc569640b519c00b0313be88bf1e /lib/vsprintf.c
parent214f766ea0909e743122966c4617b3a112e405d7 (diff)
downloadlinux-da99075c1d368315e1508b6143226c0d27b621e0.tar.gz
lib/vsprintf.c: improve standard conformance of sscanf()
Xen's pciback points out a couple of deficiencies with vsscanf()'s standard conformance: - Trailing character matching cannot be checked by the caller: With a format string of "(%x:%x.%x) %n" absence of the closing parenthesis cannot be checked, as input of "(00:00.0)" doesn't cause the %n to be evaluated (because of the code not skipping white space before the trailing %n). - The parameter corresponding to a trailing %n could get filled even if there was a matching error: With a format string of "(%x:%x.%x)%n", input of "(00:00.0]" would still fill the respective variable pointed to (and hence again make the mismatch non-detectable by the caller). This patch aims at fixing those, but leaves other non-conforming aspects of it untouched, among them these possibly relevant ones: - improper handling of the assignment suppression character '*' (blindly discarding all succeeding non-white space from the format and input strings), - not honoring conversion specifiers for %n, - not recognizing the C99 conversion specifier 't' (recognized by vsprintf()). Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/vsprintf.c')
-rw-r--r--lib/vsprintf.c33
1 files changed, 14 insertions, 19 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 9287e254993..39c99fea7c0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2017,7 +2017,7 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
s16 field_width;
bool is_sign;
- while (*fmt && *str) {
+ while (*fmt) {
/* skip any white space in format */
/* white space in format matchs any amount of
* white space, including none, in the input.
@@ -2042,6 +2042,8 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
* advance both strings to next white space
*/
if (*fmt == '*') {
+ if (!*str)
+ break;
while (!isspace(*fmt) && *fmt != '%' && *fmt)
fmt++;
while (!isspace(*str) && *str)
@@ -2070,7 +2072,17 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
}
}
- if (!*fmt || !*str)
+ if (!*fmt)
+ break;
+
+ if (*fmt == 'n') {
+ /* return number of characters read so far */
+ *va_arg(args, int *) = str - buf;
+ ++fmt;
+ continue;
+ }
+
+ if (!*str)
break;
base = 10;
@@ -2103,13 +2115,6 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
num++;
}
continue;
- case 'n':
- /* return number of characters read so far */
- {
- int *i = (int *)va_arg(args, int*);
- *i = str - buf;
- }
- continue;
case 'o':
base = 8;
break;
@@ -2210,16 +2215,6 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
str = next;
}
- /*
- * Now we've come all the way through so either the input string or the
- * format ended. In the former case, there can be a %n at the current
- * position in the format that needs to be filled.
- */
- if (*fmt == '%' && *(fmt + 1) == 'n') {
- int *p = (int *)va_arg(args, int *);
- *p = str - buf;
- }
-
return num;
}
EXPORT_SYMBOL(vsscanf);