From: Huang Jianan <huangjianan@oppo.com> To: linux-unionfs@vger.kernel.org, miklos@szeredi.hu, linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org Cc: huangjianan@oppo.com, guoweichao@oppo.com, yh@oppo.com, zhangshiming@oppo.com, guanyuwei@oppo.com, jnhuang95@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v3] ovl: fix null pointer when filesystem doesn't support direct IO Date: Wed, 22 Sep 2021 15:23:26 +0800 [thread overview] Message-ID: <20210922072326.3538-1-huangjianan@oppo.com> (raw) In-Reply-To: <9ef909de-1854-b4be-d272-2b4cda52329f@oppo.com> From: Huang Jianan <huangjianan@oppo.com> At present, overlayfs provides overlayfs inode to users. Overlayfs inode provides ovl_aops with noop_direct_IO to avoid open failure with O_DIRECT. But some compressed filesystems, such as erofs and squashfs, don't support direct_IO. Users who use f_mapping->a_ops->direct_IO to check O_DIRECT support, will read file through this way. This will cause overlayfs to access a non-existent direct_IO function and cause panic due to null pointer: Kernel panic - not syncing: CFI failure (target: 0x0) CPU: 6 PID: 247 Comm: loop0 Call Trace: panic+0x188/0x45c __cfi_slowpath+0x0/0x254 __cfi_slowpath+0x200/0x254 generic_file_read_iter+0x14c/0x150 vfs_iocb_iter_read+0xac/0x164 ovl_read_iter+0x13c/0x2fc lo_rw_aio+0x2bc/0x458 loop_queue_work+0x4a4/0xbc0 kthread_worker_fn+0xf8/0x1d0 loop_kthread_worker_fn+0x24/0x38 kthread+0x29c/0x310 ret_from_fork+0x10/0x30 The filesystem may only support direct_IO for some file types. For example, erofs supports direct_IO for uncompressed files. So return -EINVAL when the file doesn't support direct_IO to fix this problem. Fixes: 5b910bd615ba ("ovl: fix GPF in swapfile_activate of file from overlayfs over xfs") Signed-off-by: Huang Jianan <huangjianan@oppo.com> --- change since v2: - Return error in ovl_open directly. (Chengguang Xu) Change since v1: - Return error to user rather than fall back to buffered io. (Chengguang Xu) fs/overlayfs/file.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index d081faa55e83..a0c99ea35daf 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -157,6 +157,10 @@ static int ovl_open(struct inode *inode, struct file *file) if (IS_ERR(realfile)) return PTR_ERR(realfile); + if ((f->f_flags & O_DIRECT) && (!realfile->f_mapping->a_ops || + !realfile->f_mapping->a_ops->direct_IO)) + return -EINVAL; + file->private_data = realfile; return 0; -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Huang Jianan via Linux-erofs <linux-erofs@lists.ozlabs.org> To: linux-unionfs@vger.kernel.org, miklos@szeredi.hu, linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org Cc: zhangshiming@oppo.com, linux-kernel@vger.kernel.org, yh@oppo.com, guanyuwei@oppo.com, linux-fsdevel@vger.kernel.org, guoweichao@oppo.com Subject: [PATCH v3] ovl: fix null pointer when filesystem doesn't support direct IO Date: Wed, 22 Sep 2021 15:23:26 +0800 [thread overview] Message-ID: <20210922072326.3538-1-huangjianan@oppo.com> (raw) In-Reply-To: <9ef909de-1854-b4be-d272-2b4cda52329f@oppo.com> From: Huang Jianan <huangjianan@oppo.com> At present, overlayfs provides overlayfs inode to users. Overlayfs inode provides ovl_aops with noop_direct_IO to avoid open failure with O_DIRECT. But some compressed filesystems, such as erofs and squashfs, don't support direct_IO. Users who use f_mapping->a_ops->direct_IO to check O_DIRECT support, will read file through this way. This will cause overlayfs to access a non-existent direct_IO function and cause panic due to null pointer: Kernel panic - not syncing: CFI failure (target: 0x0) CPU: 6 PID: 247 Comm: loop0 Call Trace: panic+0x188/0x45c __cfi_slowpath+0x0/0x254 __cfi_slowpath+0x200/0x254 generic_file_read_iter+0x14c/0x150 vfs_iocb_iter_read+0xac/0x164 ovl_read_iter+0x13c/0x2fc lo_rw_aio+0x2bc/0x458 loop_queue_work+0x4a4/0xbc0 kthread_worker_fn+0xf8/0x1d0 loop_kthread_worker_fn+0x24/0x38 kthread+0x29c/0x310 ret_from_fork+0x10/0x30 The filesystem may only support direct_IO for some file types. For example, erofs supports direct_IO for uncompressed files. So return -EINVAL when the file doesn't support direct_IO to fix this problem. Fixes: 5b910bd615ba ("ovl: fix GPF in swapfile_activate of file from overlayfs over xfs") Signed-off-by: Huang Jianan <huangjianan@oppo.com> --- change since v2: - Return error in ovl_open directly. (Chengguang Xu) Change since v1: - Return error to user rather than fall back to buffered io. (Chengguang Xu) fs/overlayfs/file.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index d081faa55e83..a0c99ea35daf 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -157,6 +157,10 @@ static int ovl_open(struct inode *inode, struct file *file) if (IS_ERR(realfile)) return PTR_ERR(realfile); + if ((f->f_flags & O_DIRECT) && (!realfile->f_mapping->a_ops || + !realfile->f_mapping->a_ops->direct_IO)) + return -EINVAL; + file->private_data = realfile; return 0; -- 2.25.1
next prev parent reply other threads:[~2021-09-22 7:23 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-18 12:13 [PATCH] ovl: fix null pointer when filesystem doesn't support direct IO Huang Jianan 2021-09-18 12:13 ` Huang Jianan via Linux-erofs 2021-09-22 1:56 ` Chengguang Xu 2021-09-22 1:56 ` Chengguang Xu 2021-09-22 3:39 ` Huang Jianan 2021-09-22 3:39 ` Huang Jianan via Linux-erofs 2021-09-22 3:47 ` [PATCH v2] " Huang Jianan 2021-09-22 3:47 ` Huang Jianan via Linux-erofs 2021-09-22 5:09 ` Chengguang Xu 2021-09-22 5:09 ` Chengguang Xu 2021-09-22 7:18 ` Huang Jianan 2021-09-22 7:18 ` Huang Jianan via Linux-erofs 2021-09-22 7:23 ` Huang Jianan [this message] 2021-09-22 7:23 ` [PATCH v3] " Huang Jianan via Linux-erofs 2021-09-22 8:06 ` Chengguang Xu 2021-09-22 8:06 ` Chengguang Xu 2021-09-22 8:24 ` Huang Jianan 2021-09-22 8:24 ` Huang Jianan via Linux-erofs 2021-09-22 13:20 ` [PATCH v3] ovl: fix null pointer when filesystemdoesn'tsupportdirect IO Chengguang Xu 2021-09-22 13:20 ` Chengguang Xu 2021-09-22 14:00 ` Miklos Szeredi 2021-09-22 14:00 ` Miklos Szeredi 2021-09-27 9:38 ` Miklos Szeredi 2021-09-27 9:38 ` Miklos Szeredi 2021-09-28 7:01 ` Huang Jianan 2021-09-28 7:01 ` Huang Jianan via Linux-erofs 2021-09-28 7:17 ` Miklos Szeredi 2021-09-28 7:17 ` Miklos Szeredi
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