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 41EBE3563D4; Fri, 24 Apr 2026 13:43:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038192; cv=none; b=q/wggQkgIJOUcO8OoSb9AC517d9/tX274IV+rygqws7nti3DiNsfGNvrCs6fbnaClIfziJQVoO/NMTydXCjlpZWUVaR4rawzrdXQMH+1jJD03Zps+yhwk3ps7x7yvAIr9V0ucSDOiIK0tEDVYJURZrZuWhDz16zr8lJV+Oi7yeo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038192; c=relaxed/simple; bh=dwFhy7mJI28lYmA1bU4x3DrfJ6vlmWmCG1lwVzSohCM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GqGJobaM6TBgfkwqKwQ0Nx439QVXdM48uRmFYD8j877/Ou0qFGYQiBFos2kcPlACsmfKEFxrT8wan8Tx7dSxTFyyBtkt1hNraYS59upFqwfudnMmkqfMiirkORSWUik8Y6S3cMDA1Qba5ajaqZl99H0wWwqhrkyDVFZzpyUNdCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kAzrnGXf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kAzrnGXf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB15AC19425; Fri, 24 Apr 2026 13:43:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038192; bh=dwFhy7mJI28lYmA1bU4x3DrfJ6vlmWmCG1lwVzSohCM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kAzrnGXfxGUc58qkecmybzehub3vnpWua4dwL7F7kVOh6K0/Ful3270ZJjI/9mnnX UbvOYEEz7FPxvi3KeP+iTHokQhlLn+nkUmFztOgVVL3aMjWGxl/xGy+vsEOf5gGJfP B1m4nkf81rGGGEo67apsPuIYvrIQM7DPXBLT7oEo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com, Yongpeng Yang , Chao Yu , Jaegeuk Kim Subject: [PATCH 6.18 28/55] f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io() Date: Fri, 24 Apr 2026 15:31:07 +0200 Message-ID: <20260424132435.863868097@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132430.006424517@linuxfoundation.org> References: <20260424132430.006424517@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yongpeng Yang commit 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 upstream. The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition. Cc: stable@kernel.org Fixes: 50fa53eccf9f ("f2fs: fix to avoid broken of dnode block list") Reported-by: syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman --- fs/f2fs/data.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -363,6 +363,8 @@ static void f2fs_write_end_io(struct bio folio->index, NODE_TYPE_REGULAR, true); f2fs_bug_on(sbi, folio->index != nid_of_node(folio)); } + if (f2fs_in_warm_node_list(sbi, folio)) + f2fs_del_fsync_node_entry(sbi, folio); dec_page_count(sbi, type); @@ -374,8 +376,6 @@ static void f2fs_write_end_io(struct bio wq_has_sleeper(&sbi->cp_wait)) wake_up(&sbi->cp_wait); - if (f2fs_in_warm_node_list(sbi, folio)) - f2fs_del_fsync_node_entry(sbi, folio); folio_clear_f2fs_gcing(folio); folio_end_writeback(folio); }