kernel/linux.git/fs/overlayfs, branch v5.15.208

ovl: Fix uninit-value in ovl_fill_real

2026-03-04T12:19:47+00:00

[ Upstream commit 1992330d90dd766fcf1730fd7bf2d6af65370ac4 ] Syzbot reported a KMSAN uninit-value issue in ovl_fill_real. This iusse's call chain is: __do_sys_getdents64() -> iterate_dir() ... -> ext4_readdir() -> fscrypt_fname_alloc_buffer() // alloc -> fscrypt_fname_disk_to_usr // write without tail '\0' -> dir_emit() -> ovl_fill_real() // read by strcmp() The string is used to store the decrypted directory entry name for an encrypted inode. As shown in the call chain, fscrypt_fname_disk_to_usr() write it without null-terminate. However, ovl_fill_real() uses strcmp() to compare the name against "..", which assumes a null-terminated string and may trigger a KMSAN uninit-value warning when the buffer tail contains uninit data. Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d130f98b2c265fae5297 Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs") Signed-off-by: Qing Wang Signed-off-by: Amir Goldstein Link: https://patch.msgid.link/20260128132406.23768-2-amir73il@gmail.com Acked-by: Miklos Szeredi Reviewed-by: Eric Biggers Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

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

2025-07-10T13:57:34+00:00

[ 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

ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up

2025-03-13T11:50:55+00:00

[ Upstream commit c84e125fff2615b4d9c259e762596134eddd2f27 ] The issue was caused by dput(upper) being called before ovl_dentry_update_reval(), while upper->d_flags was still accessed in ovl_dentry_remote(). Move dput(upper) after its last use to prevent use-after-free. BUG: KASAN: slab-use-after-free in ovl_dentry_remote fs/overlayfs/util.c:162 [inline] BUG: KASAN: slab-use-after-free in ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 ovl_dentry_remote fs/overlayfs/util.c:162 [inline] ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167 ovl_link_up fs/overlayfs/copy_up.c:610 [inline] ovl_copy_up_one+0x2105/0x3490 fs/overlayfs/copy_up.c:1170 ovl_copy_up_flags+0x18d/0x200 fs/overlayfs/copy_up.c:1223 ovl_rename+0x39e/0x18c0 fs/overlayfs/dir.c:1136 vfs_rename+0xf84/0x20a0 fs/namei.c:4893 ... Fixes: b07d5cc93e1b ("ovl: update of dentry revalidate flags after copy up") Reported-by: syzbot+316db8a1191938280eb6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=316db8a1191938280eb6 Signed-off-by: Vasiliy Kovalev Link: https://lore.kernel.org/r/20250214215148.761147-1-kovalev@altlinux.org Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

ovl: pass ofs to creation operations

2025-03-13T11:50:55+00:00

[ Upstream commit 576bb263450bbba6601a9f528d0cf601d97a13e6 ] Pass down struct ovl_fs to all creation helpers so we can ultimately retrieve the relevant upper mount and take the mount's idmapping into account when creating new filesystem objects. This is needed to support idmapped base layers with overlay. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi Stable-dep-of: c84e125fff26 ("ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up") Signed-off-by: Sasha Levin

ovl: use wrappers to all vfs_*xattr() calls

2025-03-13T11:50:55+00:00

[ Upstream commit c914c0e27eb0843b7cf3bec71d6f34d53a3a671e ] Use helpers ovl_*xattr() to access user/trusted.overlay.* xattrs and use helpers ovl_do_*xattr() to access generic xattrs. This is a preparatory patch for using idmapped base layers with overlay. Note that a few of those places called vfs_*xattr() calls directly to reduce the amount of debug output. But as Miklos pointed out since overlayfs has been stable for quite some time the debug output isn't all that relevant anymore and the additional debug in all locations was actually quite helpful when developing this patch series. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi Stable-dep-of: c84e125fff26 ("ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up") Signed-off-by: Sasha Levin

ovl: properly handle large files in ovl_security_fileattr

2024-12-14T18:51:23+00:00

commit 3b6b99ef15ea37635604992ede9ebcccef38a239 upstream. dentry_open in ovl_security_fileattr fails for any file larger than 2GB if open method of the underlying filesystem calls generic_file_open (e.g. fusefs). The issue can be reproduce using the following script: (passthrough_ll is an example app from libfuse). $ D=/opt/test/mnt $ mkdir -p ${D}/{source,base,top/uppr,top/work,ovlfs} $ dd if=/dev/zero of=${D}/source/zero.bin bs=1G count=2 $ passthrough_ll -o source=${D}/source ${D}/base $ mount -t overlay overlay \ -olowerdir=${D}/base,upperdir=${D}/top/uppr,workdir=${D}/top/work \ ${D}/ovlfs $ chmod 0777 ${D}/mnt/ovlfs/zero.bin Running this script results in "Value too large for defined data type" error message from chmod. Signed-off-by: Oleksandr Tymoshenko Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags") Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

ovl: Filter invalid inodes with missing lookup function

2024-12-14T18:50:33+00:00

commit c8b359dddb418c60df1a69beea01d1b3322bfe83 upstream. 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 Signed-off-by: Greg Kroah-Hartman

ima: detect changes to the backing overlay file

2023-11-28T16:56:29+00:00

commit b836c4d29f2744200b2af41e14bf50758dddc818 upstream. Commit 18b44bc5a672 ("ovl: Always reevaluate the file signature for IMA") forced signature re-evaulation on every file access. Instead of always re-evaluating the file's integrity, detect a change to the backing file, by comparing the cached file metadata with the backing file's metadata. Verifying just the i_version has not changed is insufficient. In addition save and compare the i_ino and s_dev as well. Reviewed-by: Amir Goldstein Tested-by: Eric Snowberg Tested-by: Raul E Rangel Cc: stable@vger.kernel.org Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

overlayfs: set ctime when setting mtime and atime

2023-10-25T09:58:59+00:00

[ Upstream commit 03dbab3bba5f009d053635c729d1244f2c8bad38 ] Nathan reported that he was seeing the new warning in setattr_copy_mgtime pop when starting podman containers. Overlayfs is trying to set the atime and mtime via notify_change without also setting the ctime. POSIX states that when the atime and mtime are updated via utimes() that we must also update the ctime to the current time. The situation with overlayfs copy-up is analogies, so add ATTR_CTIME to the bitmask. notify_change will fill in the value. Reported-by: Nathan Chancellor Signed-off-by: Jeff Layton Tested-by: Nathan Chancellor Acked-by: Christian Brauner Acked-by: Amir Goldstein Message-Id: <20230913-ctime-v1-1-c6bc509cbc27@kernel.org> Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

ovl: fix incorrect fdput() on aio completion

2023-09-23T09:10:01+00:00

commit 724768a39374d35b70eaeae8dd87048a2ec7ae8e upstream. ovl_{read,write}_iter() always call fdput(real) to put one or zero refcounts of the real file, but for aio, whether it was submitted or not, ovl_aio_put() also calls fdput(), which is not balanced. This is only a problem in the less common case when FDPUT_FPUT flag is set. To fix the problem use get_file() to take file refcount and use fput() instead of fdput() in ovl_aio_put(). Fixes: 2406a307ac7d ("ovl: implement async IO routines") Cc: # v5.6 Reviewed-by: Miklos Szeredi Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman