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 E99BF1DC19F; Wed, 5 Feb 2025 15:10:56 +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=1738768257; cv=none; b=KjqasOu9HdaLZ5ug6qVB99vHcxxVaRYxJWRwyrxfDKeXFXdJUqudaCOGOyversEan4nHL/r0apgq8fkq5dx152Xu1YISWU3+Rc8S046igEPwtb8+Du8jb0s2s9/CnN0mzBzL1h3YR1Xi9HYQ/XCh4PUym6lrRg6d/KB0Gu38CUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738768257; c=relaxed/simple; bh=dWtOlbqt6mx2TVlh/vqNomMFE1dCKAe9fpHyAhdKQIw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ji2yHQ0ET1FtaUP+ZB7F1q5rg2KOrleZVSYF8Ftad9Cs0GRK8qEfDrm6RhP1nO8i4vRkdrmRlhaFnDDfjgeo1RbV10+RZUb/nrfBzfJ4OSOS+8za1TuebamVDgUyW/BWiNiz4RGNYaPoc7WEfyR+6gMe4Y88vG5hVglMITlkf60= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T/bWg8B0; 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="T/bWg8B0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6842C4CED6; Wed, 5 Feb 2025 15:10:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738768256; bh=dWtOlbqt6mx2TVlh/vqNomMFE1dCKAe9fpHyAhdKQIw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T/bWg8B0cohW1vlZifsDjvr1nlZeDnMgpmDLB2TuB6qxC5YROM8Ma05eoNrJKkKPY RBs6oY1uMo09a+F4HdtlwRNW6NpXy0llZliCENcjXC5jGTwpl4AjOkienici4jB4F+ 1x8zvYALpYRxPqOewerL4Rh49ve7HIEdce7v13s0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Song Liu , Harshit Mogalapalli Subject: [PATCH 6.12 574/590] md/md-bitmap: Synchronize bitmap_get_stats() with bitmap lifetime Date: Wed, 5 Feb 2025 14:45:29 +0100 Message-ID: <20250205134517.226476671@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250205134455.220373560@linuxfoundation.org> References: <20250205134455.220373560@linuxfoundation.org> User-Agent: quilt/0.68 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Kuai commit 8d28d0ddb986f56920ac97ae704cc3340a699a30 upstream. After commit ec6bb299c7c3 ("md/md-bitmap: add 'sync_size' into struct md_bitmap_stats"), following panic is reported: Oops: general protection fault, probably for non-canonical address RIP: 0010:bitmap_get_stats+0x2b/0xa0 Call Trace: md_seq_show+0x2d2/0x5b0 seq_read_iter+0x2b9/0x470 seq_read+0x12f/0x180 proc_reg_read+0x57/0xb0 vfs_read+0xf6/0x380 ksys_read+0x6c/0xf0 do_syscall_64+0x82/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e Root cause is that bitmap_get_stats() can be called at anytime if mddev is still there, even if bitmap is destroyed, or not fully initialized. Deferenceing bitmap in this case can crash the kernel. Meanwhile, the above commit start to deferencing bitmap->storage, make the problem easier to trigger. Fix the problem by protecting bitmap_get_stats() with bitmap_info.mutex. Cc: stable@vger.kernel.org # v6.12+ Fixes: 32a7627cf3a3 ("[PATCH] md: optimised resync using Bitmap based intent logging") Reported-and-tested-by: Harshit Mogalapalli Closes: https://lore.kernel.org/linux-raid/ca3a91a2-50ae-4f68-b317-abd9889f3907@oracle.com/T/#m6e5086c95201135e4941fe38f9efa76daf9666c5 Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20250124092055.4050195-1-yukuai1@huaweicloud.com Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman --- drivers/md/md-bitmap.c | 5 ++++- drivers/md/md.c | 5 +++++ 2 files changed, 9 insertions(+), 1 deletion(-) --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -2355,7 +2355,10 @@ static int bitmap_get_stats(void *data, if (!bitmap) return -ENOENT; - + if (bitmap->mddev->bitmap_info.external) + return -ENOENT; + if (!bitmap->storage.sb_page) /* no superblock */ + return -EINVAL; sb = kmap_local_page(bitmap->storage.sb_page); stats->sync_size = le64_to_cpu(sb->sync_size); kunmap_local(sb); --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8376,6 +8376,10 @@ static int md_seq_show(struct seq_file * return 0; spin_unlock(&all_mddevs_lock); + + /* prevent bitmap to be freed after checking */ + mutex_lock(&mddev->bitmap_info.mutex); + spin_lock(&mddev->lock); if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) { seq_printf(seq, "%s : ", mdname(mddev)); @@ -8451,6 +8455,7 @@ static int md_seq_show(struct seq_file * seq_printf(seq, "\n"); } spin_unlock(&mddev->lock); + mutex_unlock(&mddev->bitmap_info.mutex); spin_lock(&all_mddevs_lock); if (mddev == list_last_entry(&all_mddevs, struct mddev, all_mddevs))