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 6897B6AA0; Tue, 5 Dec 2023 03:22:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HtuFlOmZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D08D9C433C7; Tue, 5 Dec 2023 03:22:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1701746556; bh=wceJK5lDJsavwpUzH5ow/HxbNbwbckFhO3oRTrjByqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HtuFlOmZQTjFTgwt9qNMkOx4A0dqJXLXlanDcOBcT46JiAMqm8+0CxCfu0zqwGlGo VROgNp+Thtxpmjebbc0ipVVIfM/NiLBJ0WwEw4R6vwKK/8mQ25R58gff+3MjIFd9vY N11h6Ucne21tSTny+M3HZm9hgRnSmmKUerkJ3MmA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Filipe Manana , Qu Wenruo , David Sterba Subject: [PATCH 6.6 069/134] btrfs: free the allocated memory if btrfs_alloc_page_array() fails Date: Tue, 5 Dec 2023 12:15:41 +0900 Message-ID: <20231205031539.903813767@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231205031535.163661217@linuxfoundation.org> References: <20231205031535.163661217@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qu Wenruo commit 94dbf7c0871f7ae6349ba4b0341ce8f5f98a071d upstream. [BUG] If btrfs_alloc_page_array() fail to allocate all pages but part of the slots, then the partially allocated pages would be leaked in function btrfs_submit_compressed_read(). [CAUSE] As explicitly stated, if btrfs_alloc_page_array() returned -ENOMEM, caller is responsible to free the partially allocated pages. For the existing call sites, most of them are fine: - btrfs_raid_bio::stripe_pages Handled by free_raid_bio(). - extent_buffer::pages[] Handled btrfs_release_extent_buffer_pages(). - scrub_stripe::pages[] Handled by release_scrub_stripe(). But there is one exception in btrfs_submit_compressed_read(), if btrfs_alloc_page_array() failed, we didn't cleanup the array and freed the array pointer directly. Initially there is still the error handling in commit dd137dd1f2d7 ("btrfs: factor out allocating an array of pages"), but later in commit 544fe4a903ce ("btrfs: embed a btrfs_bio into struct compressed_bio"), the error handling is removed, leading to the possible memory leak. [FIX] This patch would add back the error handling first, then to prevent such situation from happening again, also Make btrfs_alloc_page_array() to free the allocated pages as a extra safety net, then we don't need to add the error handling to btrfs_submit_compressed_read(). Fixes: 544fe4a903ce ("btrfs: embed a btrfs_bio into struct compressed_bio") CC: stable@vger.kernel.org # 6.4+ Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/extent_io.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -675,8 +675,8 @@ static void end_bio_extent_readpage(stru * the array will be skipped * * Return: 0 if all pages were able to be allocated; - * -ENOMEM otherwise, and the caller is responsible for freeing all - * non-null page pointers in the array. + * -ENOMEM otherwise, the partially allocated pages would be freed and + * the array slots zeroed */ int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array) { @@ -695,8 +695,13 @@ int btrfs_alloc_page_array(unsigned int * though alloc_pages_bulk_array() falls back to alloc_page() * if it could not bulk-allocate. So we must be out of memory. */ - if (allocated == last) + if (allocated == last) { + for (int i = 0; i < allocated; i++) { + __free_page(page_array[i]); + page_array[i] = NULL; + } return -ENOMEM; + } memalloc_retry_wait(GFP_NOFS); }