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 F003F3A8F4; Fri, 24 Nov 2023 18:31:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DVoGgJfn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7BBB6C433C8; Fri, 24 Nov 2023 18:31:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700850718; bh=AY9MnlDKRJfDVtJfJ2p3hOZRkiOkA2l4ckK3Jag/CEE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DVoGgJfn8HWko8tyGiiFjlx9UX7QX+n9dGk6FZJbwemr4mNu7OuoB/c1FwVVJBW1U BXxfzjho7yU2D3/ubmMHmln/d2WoPVj6cq6dvhovMxgCQtarWcjdJk5FKeuEjfU4Lz 8KaWblVt8jnCt2PS/76SoBtwOONmk3U9A68uV3CY= 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 6.5 137/491] gfs2: fix an oops in gfs2_permission Date: Fri, 24 Nov 2023 17:46:13 +0000 Message-ID: <20231124172028.612844547@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172024.664207345@linuxfoundation.org> References: <20231124172024.664207345@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 6.5-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 17c994a0c0d09..117b4b5a03072 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -1862,14 +1862,21 @@ int gfs2_permission(struct mnt_idmap *idmap, 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 9f4d5d6549ee6..f98ddb9d19a21 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -1558,7 +1558,7 @@ 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