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Fri, 14 Nov 2025 07:53:14 -0800 (PST) Received: from bhk ([196.239.132.233]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47795751d08sm8972205e9.7.2025.11.14.07.53.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 07:53:13 -0800 (PST) From: Mehdi Ben Hadj Khelifa To: viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, syzbot+ad45f827c88778ff7df6@syzkaller.appspotmail.com Cc: frank.li@vivo.com, glaubitz@physik.fu-berlin.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, slava@dubeyko.com, syzkaller-bugs@googlegroups.com, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, khalid@kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Mehdi Ben Hadj Khelifa Subject: [PATCH] fs/super: fix memory leak of s_fs_info on setup_bdev_super failure Date: Fri, 14 Nov 2025 17:52:27 +0100 Message-ID: <20251114165255.101361-1-mehdi.benhadjkhelifa@gmail.com> X-Mailer: git-send-email 2.51.2 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Failure in setup_bdev_super() triggers an error path where fc->s_fs_info ownership has already been transferred to the superblock via sget_fc() call in get_tree_bdev_flags() and calling put_fs_context() in do_new_mount() to free the s_fs_info for the specific filesystem gets passed in a NULL pointer. Pass back the ownership of the s_fs_info pointer to the filesystem context once the error path has been triggered to be cleaned up gracefully in put_fs_context(). Fixes: cb50b348c71f ("convenience helpers: vfs_get_super() and sget_fc()") Reported-by: syzbot+ad45f827c88778ff7df6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ad45f827c88778ff7df6 Signed-off-by: Mehdi Ben Hadj Khelifa --- Note:This patch might need some more testing as I only did run selftests with no regression, check dmesg output for no regression, run reproducer with no bug. fs/super.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/super.c b/fs/super.c index 5bab94fb7e03..8fadf97fcc42 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1690,6 +1690,11 @@ int get_tree_bdev_flags(struct fs_context *fc, if (!error) error = fill_super(s, fc); if (error) { + /* + * return s_fs_info ownership to fc to be cleaned up by put_fs_context() + */ + fc->s_fs_info = s->s_fs_info; + s->s_fs_info = NULL; deactivate_locked_super(s); return error; } -- 2.51.2