linux-ext4 - [PATCH v3 1/5] ext4: fix memory leak in parse_apply_sb_mount

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Date:   Fri, 13 May 2022 16:16:01 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     linux-fscrypt@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     Jeff Layton <jlayton@...nel.org>,
        Lukas Czerner <lczerner@...hat.com>,
        Theodore Ts'o <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v3 1/5] ext4: fix memory leak in parse_apply_sb_mount_options()

From: Eric Biggers <ebiggers@...gle.com>

If processing the on-disk mount options fails after any memory was
allocated in the ext4_fs_context, e.g. s_qf_names, then this memory is
leaked.  Fix this by calling ext4_fc_free() instead of kfree() directly.

Reproducer:

    mkfs.ext4 -F /dev/vdc
    tune2fs /dev/vdc -E mount_opts=usrjquota=file
    echo clear > /sys/kernel/debug/kmemleak
    mount /dev/vdc /vdc
    echo scan > /sys/kernel/debug/kmemleak
    sleep 5
    echo scan > /sys/kernel/debug/kmemleak
    cat /sys/kernel/debug/kmemleak

Fixes: 7edfd85b1ffd ("ext4: Completely separate options parsing and sb setup")
Cc: stable@...r.kernel.org
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 fs/ext4/super.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1466fbdbc8e34..60fa2f2623e07 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2625,8 +2625,10 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
 	ret = ext4_apply_options(fc, sb);
 
 out_free:
-	kfree(s_ctx);
-	kfree(fc);
+	if (fc) {
+		ext4_fc_free(fc);
+		kfree(fc);
+	}
 	kfree(s_mount_opts);
 	return ret;
 }
-- 
2.36.1