[PATCH 5.4 33/54] coredump: fix core_pattern parse error

[Greg Kroah-Hartman]

From: Menglong Dong <dong.menglong@xxxxxxxxxx>

commit 2bf509d96d84c3336d08375e8af34d1b85ee71c8 upstream.

'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@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul Wise <pabs3@xxxxxxxxxxxxx>
Cc: Jakub Wilk <jwilk@xxxxxxxxx> [https://bugs.debian.org/924398]
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/5fb62870.1c69fb81.8ef5d.af76@xxxxxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/coredump.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -224,7 +224,8 @@ static int format_corename(struct core_n
 		 */
 		if (ispipe) {
 			if (isspace(*pat_ptr)) {
-				was_space = true;
+				if (cn->used != 0)
+					was_space = true;
 				pat_ptr++;
 				continue;
 			} else if (was_space) {