kernel.git/fs/overlayfs/util.c, branch linux-6.15.y

ovl: Check for NULL d_inode() in ovl_dentry_upper()

2025-07-06T09:04:09Z

[ Upstream commit 8a39f1c870e9d6fbac5638f3a42a6a6363829c49 ] In ovl_path_type() and ovl_is_metacopy_dentry() GCC notices that it is possible for OVL_E() to return NULL (which implies that d_inode(dentry) may be NULL). This would result in out of bounds reads via container_of(), seen with GCC 15's -Warray-bounds -fdiagnostics-details. For example: In file included from arch/x86/include/generated/asm/rwonce.h:1, from include/linux/compiler.h:339, from include/linux/export.h:5, from include/linux/linkage.h:7, from include/linux/fs.h:5, from fs/overlayfs/util.c:7: In function 'ovl_upperdentry_dereference', inlined from 'ovl_dentry_upper' at ../fs/overlayfs/util.c:305:9, inlined from 'ovl_path_type' at ../fs/overlayfs/util.c:216:6: include/asm-generic/rwonce.h:44:26: error: array subscript 0 is outside array bounds of 'struct inode[7486503276667837]' [-Werror=array-bounds=] 44 | #define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) | ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/asm-generic/rwonce.h:50:9: note: in expansion of macro '__READ_ONCE' 50 | __READ_ONCE(x); \ | ^~~~~~~~~~~ fs/overlayfs/ovl_entry.h:195:16: note: in expansion of macro 'READ_ONCE' 195 | return READ_ONCE(oi->__upperdentry); | ^~~~~~~~~ 'ovl_path_type': event 1 185 | return inode ? OVL_I(inode)->oe : NULL; 'ovl_path_type': event 2 Avoid this by allowing ovl_dentry_upper() to return NULL if d_inode() is NULL, as that means the problematic dereferencing can never be reached. Note that this fixes the over-eager compiler warning in an effort to being able to enable -Warray-bounds globally. There is no known behavioral bug here. Suggested-by: Amir Goldstein Signed-off-by: Kees Cook Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

tree-wide: s/revert_creds_light()/revert_creds()/g

2024-12-02T10:25:09Z

Rename all calls to revert_creds_light() back to revert_creds(). Link: https://lore.kernel.org/r/20241125-work-cred-v2-6-68b9d38bb5b2@kernel.org Reviewed-by: Jeff Layton Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner

tree-wide: s/override_creds_light()/override_creds()/g

2024-12-02T10:25:09Z

Rename all calls to override_creds_light() back to overrid_creds(). Link: https://lore.kernel.org/r/20241125-work-cred-v2-5-68b9d38bb5b2@kernel.org Reviewed-by: Jeff Layton Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner

ovl: Filter invalid inodes with missing lookup function

2024-11-20T09:23:04Z

Add a check to the ovl_dentry_weird() function to prevent the processing of directory inodes that lack the lookup function. This is important because such inodes can cause errors in overlayfs when passed to the lowerstack. Reported-by: syzbot+a8c9d476508bd14a90e5@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=a8c9d476508bd14a90e5 Suggested-by: Miklos Szeredi Link: https://lore.kernel.org/linux-unionfs/CAJfpegvx-oS9XGuwpJx=Xe28_jzWx5eRo1y900_ZzWY+=gGzUg@mail.gmail.com/ Signed-off-by: Vasiliy Kovalev Cc: Signed-off-by: Amir Goldstein

ovl: Optimize override/revert creds

2024-11-15T07:55:39Z

Use override_creds_light() in ovl_override_creds() and revert_creds_light() in ovl_revert_creds(). The _light() functions do not change the 'usage' of the credentials in question, as they refer to the credentials associated with the mounter, which have a longer lifetime. In ovl_setup_cred_for_create(), do not need to modify the mounter credentials (returned by override_creds_light()) 'usage' counter. Add a warning to verify that we are indeed working with the mounter credentials (stored in the superblock). Failure in this assumption means that creds may leak. Suggested-by: Christian Brauner Signed-off-by: Vinicius Costa Gomes Signed-off-by: Amir Goldstein

ovl: use wrapper ovl_revert_creds()

2024-11-11T09:45:04Z

Introduce ovl_revert_creds() wrapper of revert_creds() to match callers of ovl_override_creds(). Suggested-by: Amir Goldstein Signed-off-by: Vinicius Costa Gomes Signed-off-by: Amir Goldstein

kernel_file_open(): get rid of inode argument

2024-04-15T20:03:24Z

always equal to ->dentry->d_inode of the path argument these days. Reviewed-by: Christian Brauner Signed-off-by: Al Viro

Merge tag 'vfs-6.9.uuid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-03-11T18:02:06Z

Pull vfs uuid updates from Christian Brauner: "This adds two new ioctl()s for getting the filesystem uuid and retrieving the sysfs path based on the path of a mounted filesystem. Getting the filesystem uuid has been implemented in filesystem specific code for a while it's now lifted as a generic ioctl" * tag 'vfs-6.9.uuid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: xfs: add support for FS_IOC_GETFSSYSFSPATH fs: add FS_IOC_GETFSSYSFSPATH fat: Hook up sb->s_uuid fs: FS_IOC_GETUUID ovl: convert to super_set_uuid() fs: super_set_uuid()

ovl: convert to super_set_uuid()

2024-02-08T20:20:11Z

We don't want to be settingc sb->s_uuid directly anymore, as there's a length field that also has to be set, and this conversion was not completely trivial. Acked-by: Amir Goldstein Signed-off-by: Kent Overstreet Link: https://lore.kernel.org/r/20240207025624.1019754-3-kent.overstreet@linux.dev Cc: Miklos Szeredi Cc: linux-unionfs@vger.kernel.org Signed-off-by: Christian Brauner

ovl: mark xwhiteouts directory with overlay.opaque='x'

2024-01-23T10:39:48Z

An opaque directory cannot have xwhiteouts, so instead of marking an xwhiteouts directory with a new xattr, overload overlay.opaque xattr for marking both opaque dir ('y') and xwhiteouts dir ('x'). This is more efficient as the overlay.opaque xattr is checked during lookup of directory anyway. This also prevents unnecessary checking the xattr when reading a directory without xwhiteouts, i.e. most of the time. Note that the xwhiteouts marker is not checked on the upper layer and on the last layer in lowerstack, where xwhiteouts are not expected. Fixes: bc8df7a3dc03 ("ovl: Add an alternative type of whiteout") Cc: # v6.7 Reviewed-by: Alexander Larsson Tested-by: Alexander Larsson Signed-off-by: Amir Goldstein