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 F0EDE8476 for ; Tue, 28 Mar 2023 14:54:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6999CC4339B; Tue, 28 Mar 2023 14:54:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680015287; bh=NLvOwBAmfmEKC/d6fA8LZ3/lkBqO3t1YDa/zE/o3dBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cg/LOAfnc21XynP5q28K6KWcQ4q+HUl+/K6QcVMtE/syKJJdBa0mtS2gjNmKWknTS IdDrX5HOv+EZj2UpyRCYn9hkTj3B2eIlxk+mqCyCOSD/rbmVWBIXrdk9zMTrxDCLJy Il3xe66Njsh490O+APAX1qxTW6eKPCR+CWTCY7m4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Savino Dicanosa , Jens Axboe Subject: [PATCH 6.2 204/240] io_uring/rsrc: fix null-ptr-deref in io_file_bitmap_get() Date: Tue, 28 Mar 2023 16:42:47 +0200 Message-Id: <20230328142628.182813129@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230328142619.643313678@linuxfoundation.org> References: <20230328142619.643313678@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Savino Dicanosa commit 02a4d923e4400a36d340ea12d8058f69ebf3a383 upstream. When fixed files are unregistered, file_alloc_end and alloc_hint are not cleared. This can later cause a NULL pointer dereference in io_file_bitmap_get() if auto index selection is enabled via IORING_FILE_INDEX_ALLOC: [ 6.519129] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] [ 6.541468] RIP: 0010:_find_next_zero_bit+0x1a/0x70 [...] [ 6.560906] Call Trace: [ 6.561322] [ 6.561672] io_file_bitmap_get+0x38/0x60 [ 6.562281] io_fixed_fd_install+0x63/0xb0 [ 6.562851] ? __pfx_io_socket+0x10/0x10 [ 6.563396] io_socket+0x93/0xf0 [ 6.563855] ? __pfx_io_socket+0x10/0x10 [ 6.564411] io_issue_sqe+0x5b/0x3d0 [ 6.564914] io_submit_sqes+0x1de/0x650 [ 6.565452] __do_sys_io_uring_enter+0x4fc/0xb20 [ 6.566083] ? __do_sys_io_uring_register+0x11e/0xd80 [ 6.566779] do_syscall_64+0x3c/0x90 [ 6.567247] entry_SYSCALL_64_after_hwframe+0x72/0xdc [...] To fix the issue, set file alloc range and alloc_hint to zero after file tables are freed. Cc: stable@vger.kernel.org Fixes: 4278a0deb1f6 ("io_uring: defer alloc_hint update to io_file_bitmap_set()") Signed-off-by: Savino Dicanosa [axboe: add explicit bitmap == NULL check as well] Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/filetable.c | 3 +++ io_uring/rsrc.c | 1 + 2 files changed, 4 insertions(+) --- a/io_uring/filetable.c +++ b/io_uring/filetable.c @@ -19,6 +19,9 @@ static int io_file_bitmap_get(struct io_ unsigned long nr = ctx->file_alloc_end; int ret; + if (!table->bitmap) + return -ENFILE; + do { ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint); if (ret != nr) --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -794,6 +794,7 @@ void __io_sqe_files_unregister(struct io } #endif io_free_file_tables(&ctx->file_table); + io_file_table_set_alloc_range(ctx, 0, 0); io_rsrc_data_free(ctx->file_data); ctx->file_data = NULL; ctx->nr_user_files = 0;