linux-kernel - [PATCH] gfs2: Fix error path kobject memory leak

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Date:   Mon, 13 May 2019 21:59:04 +0200
From:   Andreas Gruenbacher <agruenba@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     cluster-devel@...hat.com, linux-kernel@...r.kernel.org,
        "Tobin C. Harding" <tobin@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andreas Gruenbacher <agruenba@...hat.com>
Subject: [PATCH] gfs2: Fix error path kobject memory leak

From: "Tobin C. Harding" <tobin@...nel.org>

If a call to kobject_init_and_add() fails we must call kobject_put()
otherwise we leak memory.

Function gfs2_sys_fs_add always calls kobject_init_and_add() which
always calls kobject_init().

It is safe to leave object destruction up to the kobject release
function and never free it manually.

Remove call to kfree() and always call kobject_put() in the error path.

Signed-off-by: Tobin C. Harding <tobin@...nel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
---
 fs/gfs2/sys.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index 1787d295834e..08e4996adc23 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -650,7 +650,6 @@ int gfs2_sys_fs_add(struct gfs2_sbd *sdp)
 	char ro[20];
 	char spectator[20];
 	char *envp[] = { ro, spectator, NULL };
-	int sysfs_frees_sdp = 0;
 
 	sprintf(ro, "RDONLY=%d", sb_rdonly(sb));
 	sprintf(spectator, "SPECTATOR=%d", sdp->sd_args.ar_spectator ? 1 : 0);
@@ -661,8 +660,6 @@ int gfs2_sys_fs_add(struct gfs2_sbd *sdp)
 	if (error)
 		goto fail_reg;
 
-	sysfs_frees_sdp = 1; /* Freeing sdp is now done by sysfs calling
-				function gfs2_sbd_release. */
 	error = sysfs_create_group(&sdp->sd_kobj, &tune_group);
 	if (error)
 		goto fail_reg;
@@ -687,10 +684,7 @@ int gfs2_sys_fs_add(struct gfs2_sbd *sdp)
 fail_reg:
 	free_percpu(sdp->sd_lkstats);
 	fs_err(sdp, "error %d adding sysfs files\n", error);
-	if (sysfs_frees_sdp)
-		kobject_put(&sdp->sd_kobj);
-	else
-		kfree(sdp);
+	kobject_put(&sdp->sd_kobj);
 	sb->s_fs_info = NULL;
 	return error;
 }
-- 
2.20.1