From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D8FA35EE6; Fri, 24 Nov 2023 19:13:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XGTGoX+a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D6F3C433C8; Fri, 24 Nov 2023 19:13:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700853229; bh=M45B7eriLNTv0XeoFN0a9UK4Pg76UoJcZrH2aFgn7EM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XGTGoX+ahab81fAZth8BnHjcmLw9aJdRmHuSo9wiO3Rab8ZdGry3MRYj72M6IZByM Ie6MgrwMYCQ27UyRwL3+aDCNvx/V/Gna/MYVx4z2dns1cw1Td6FIqqQupUqVdTmRAQ HZmCR0NnwHlFDhli6QP05idQq8RAVpChcZ/aVuok= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro , Andreas Gruenbacher , Sasha Levin Subject: [PATCH 5.15 071/297] gfs2: fix an oops in gfs2_permission Date: Fri, 24 Nov 2023 17:51:53 +0000 Message-ID: <20231124172002.731519662@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172000.087816911@linuxfoundation.org> References: <20231124172000.087816911@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro [ Upstream commit 0abd1557e21c617bd13fc18f7725fc6363c05913 ] In RCU mode, we might race with gfs2_evict_inode(), which zeroes ->i_gl. Freeing of the object it points to is RCU-delayed, so if we manage to fetch the pointer before it's been replaced with NULL, we are fine. Check if we'd fetched NULL and treat that as "bail out and tell the caller to get out of RCU mode". Signed-off-by: Al Viro Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/inode.c | 11 +++++++++-- fs/gfs2/super.c | 2 +- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index 97ee17843b4d0..682418d9c8e72 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -1850,14 +1850,21 @@ int gfs2_permission(struct user_namespace *mnt_userns, struct inode *inode, { struct gfs2_inode *ip; struct gfs2_holder i_gh; + struct gfs2_glock *gl; int error; gfs2_holder_mark_uninitialized(&i_gh); ip = GFS2_I(inode); - if (gfs2_glock_is_locked_by_me(ip->i_gl) == NULL) { + gl = rcu_dereference(ip->i_gl); + if (unlikely(!gl)) { + /* inode is getting torn down, must be RCU mode */ + WARN_ON_ONCE(!(mask & MAY_NOT_BLOCK)); + return -ECHILD; + } + if (gfs2_glock_is_locked_by_me(gl) == NULL) { if (mask & MAY_NOT_BLOCK) return -ECHILD; - error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh); + error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh); if (error) return error; } diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 51b44da4a0d64..268651ac9fc84 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -1436,7 +1436,7 @@ static void gfs2_evict_inode(struct inode *inode) wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE); gfs2_glock_add_to_lru(ip->i_gl); gfs2_glock_put_eventually(ip->i_gl); - ip->i_gl = NULL; + rcu_assign_pointer(ip->i_gl, NULL); } } -- 2.42.0