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SubjectRe: [PATCH] reiserfs: check/extend buffer length for printing functions
On 07/18/2013 03:43 PM, Al Viro wrote:
> On Thu, Jul 18, 2013 at 03:29:17PM +0800, Chen Gang wrote:
>> > On 07/18/2013 12:28 PM, Chen Gang wrote:
>>> > >
>>>> > >> strcpy(fmt1, fmt);
>>>> > >> @@ -199,46 +214,51 @@ static void prepare_error_buf(const char *fmt, va_list args)
>>>> > >> while ((k = is_there_reiserfs_struct(fmt1, &what)) != NULL) {
>>>> > >> *k = 0;
>>>> > >>
>>>> > >> - p += vsprintf(p, fmt1, args);
>>>> > >> + p += vsnprintf(p, left, fmt1, args);
>> >
>> > At least, need use vscnprintf() instead of vsnprintf(), since we need
>> > the real written length return.
> n = vsnprintf(p, left, ....);
> left -= n;
> if (left <= 0) /* overflow */
> break; /* or whatever's suitable here */
> p += n;
>
>

Yeah, it is really a better fix. :-)


And now I am just testing, and find another issue about it, I am just
analyzing it it.

For next-20130717, let reiserfs build-in, when "mount /dev/sda11
/mnt/sda11" (assume sda11 is reiserfs filesystem).

I modify the code like this (just only use vsnprintf instead of vsprintf):

--------------------------diff begin------------------------------

diff --git a/fs/reiserfs/prints.c b/fs/reiserfs/prints.c
index c0b1112..3a38a62 100644
--- a/fs/reiserfs/prints.c
+++ b/fs/reiserfs/prints.c
@@ -10,7 +10,7 @@

#include <stdarg.h>

-static char error_buf[1024];
+static char error_buf[13];
static char fmt_buf[1024];
static char off_buf[80];

@@ -195,7 +195,7 @@ static void prepare_error_buf(const char *fmt, va_list args)
spin_lock(&error_lock);

strcpy(fmt1, fmt);
-
+#if 0
while ((k = is_there_reiserfs_struct(fmt1, &what)) != NULL) {
*k = 0;

@@ -238,7 +238,8 @@ static void prepare_error_buf(const char *fmt, va_list args)
p += strlen(p);
fmt1 = k + 2;
}
- vsprintf(p, fmt1, args);
+#endif
+ vsnprintf(p, 13, fmt1, args);
spin_unlock(&error_lock);

}
--------------------------diff end--------------------------------

The output has '<7>':

[root@dhcp122 ~]# dmesg
[ 38.797073] REISERFS (device sda11): found reiser
[ 38.797089] REISERFS warning (device sda11): reiserfs_fill_super: CONFIG_REISE
[ 38.797095] REISERFS warning (device sda11): reiserfs_fill_super: - it is slow
[ 38.797098] REISERFS (device sda11): using orderereiserfs: using flush barriers
[ 38.800507] REISERFS (device sda11): journal para
[ 38.801158] REISERFS (device sda11): checking tra<7>[ 38.801165] REISERFS debug (device sda11): journal-1153
[ 38.801405] REISERFS debug (device sda11): journal-1206
[ 38.801410] REISERFS debug (device sda11): journal-1299
[ 38.817621] REISERFS (device sda11): Using r5 has
[ 38.817906] SELinux: initialized (dev sda11, type reiserfs), uses genfs_contexts



Welcome any suggestions or completions.

Thanks.
--
Chen Gang


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