[PATCH] coredump: fix core_pattern parse error

[PATCH] coredump: fix core_pattern parse error

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

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

diff --git a/fs/coredump.c b/fs/coredump.c
index 0cd9056d79cc..c6acfc694f65 100644
--- 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) {
-- 
2.25.1

Re: [PATCH] coredump: fix core_pattern parse error

[Andrew Morton]

On Thu, 19 Nov 2020 03:08:43 -0500 menglong8.dong@gmail.com wrote:

> From: Menglong Dong <dong.menglong@zte.com.cn>
> 
> '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',
> 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'.
> 
> ...
>
> --- 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) {

Looks good to me.  It's been a bit more than a year, but I'll add a
cc:stable to this so that the earlier kernels get the fix.