coredump: fix core_pattern parse error

'format_corename()' will splite 'core_pattern' on spaces when it is in
pipe mode, and take helper_argv[0] as the path to usermode executable.
It works fine in most cases.

However, if there is a space between '|' and '/file/path', such as
'| /usr/lib/systemd/systemd-coredump %P %u %g', then helper_argv[0] will
be parsed as '', and users will get a 'Core dump to | disabled'.

It is not friendly to users, as the pattern above was valid previously.
Fix this by ignoring the spaces between '|' and '/file/path'.

Fixes: 315c69261dd3 ("coredump: split pipe command whitespace before expanding template")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Wise <pabs3@bonedaddy.net>
Cc: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398]
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/5fb62870.1c69fb81.8ef5d.af76@mx.google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/coredump.c b/fs/coredump.c
index 0cd9056..c6acfc6 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -229,7 +229,8 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm,
                 */
                if (ispipe) {
                        if (isspace(*pat_ptr)) {
-                               was_space = true;
+                               if (cn->used != 0)
+                                       was_space = true;
                                pat_ptr++;
                                continue;
                        } else if (was_space) {