Encoding file handles is usually performed by a filesystem >encode_fh() method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and name_to_handle_at(2) syscall are ready to cope with the possibility of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that currently have a WARN_ON() assertion when ->encode_fh() fails. Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") in v6.6 as the regressing commit, but this is not accurate.
The aforementioned commit only increases the chances of the assertion and allows triggering the assertion with the reproducer using overlayfs, inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and other reasons of ->encode_fh() failures and more particularly, it was also possible with the exact same reproducer using overlayfs that is mounted with options index=on,nfs_export=on also on kernels < v6.6. Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@googl... Reported-by: Dmitry Safonov dima@arista.com Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F... Cc: stable@vger.kernel.org Signed-off-by: Amir Goldstein amir73il@gmail.com ---
Christian,
I could have sumbitted two independant patches to relax the assertion in fsnotify and overlayfs via fsnotify and overlayfs trees, but the nature of the problem is the same and in both cases, the problem became worse with the introduction of non-decodable file handles support, so decided to fix them together and ask you to take the fix via the vfs tree.
Please let you if you think it should be done differently.
Thanks, Amir.
fs/notify/fdinfo.c | 4 +--- fs/overlayfs/copy_up.c | 5 ++--- 2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c index dec553034027e..e933f9c65d904 100644 --- a/fs/notify/fdinfo.c +++ b/fs/notify/fdinfo.c @@ -47,10 +47,8 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode) size = f->handle_bytes >> 2;
ret = exportfs_encode_fid(inode, (struct fid *)f->f_handle, &size); - if ((ret == FILEID_INVALID) || (ret < 0)) { - WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret); + if ((ret == FILEID_INVALID) || (ret < 0)) return; - }
f->handle_type = ret; f->handle_bytes = size * sizeof(u32); diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 3601ddfeddc2e..56eee9f23ea9a 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -442,9 +442,8 @@ struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real, buflen = (dwords << 2);
err = -EIO; - if (WARN_ON(fh_type < 0) || - WARN_ON(buflen > MAX_HANDLE_SZ) || - WARN_ON(fh_type == FILEID_INVALID)) + if (fh_type < 0 || fh_type == FILEID_INVALID || + WARN_ON(buflen > MAX_HANDLE_SZ)) goto out_err;
fh->fb.version = OVL_FH_VERSION;
On Thu, Dec 19, 2024 at 12:53 PM Amir Goldstein amir73il@gmail.com wrote:
Encoding file handles is usually performed by a filesystem >encode_fh() method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and name_to_handle_at(2) syscall are ready to cope with the possibility of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that currently have a WARN_ON() assertion when ->encode_fh() fails. Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") in v6.6 as the regressing commit, but this is not accurate.
The aforementioned commit only increases the chances of the assertion and allows triggering the assertion with the reproducer using overlayfs, inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and other reasons of ->encode_fh() failures and more particularly, it was also possible with the exact same reproducer using overlayfs that is mounted with options index=on,nfs_export=on also on kernels < v6.6. Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@googl... Reported-by: Dmitry Safonov dima@arista.com Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F... Cc: stable@vger.kernel.org Signed-off-by: Amir Goldstein amir73il@gmail.com
Christian,
I could have sumbitted two independant patches to relax the assertion in fsnotify and overlayfs via fsnotify and overlayfs trees, but the nature of the problem is the same and in both cases, the problem became worse with the introduction of non-decodable file handles support, so decided to fix them together and ask you to take the fix via the vfs tree.
Please let you if you think it should be done differently.
FWIW, pushed two separate patches to branch fsnotify-fixes on my github.
I guess it is nicer this way and will help automatic backporting.
Thanks, Amir.
Thanks, Amir.
fs/notify/fdinfo.c | 4 +--- fs/overlayfs/copy_up.c | 5 ++--- 2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c index dec553034027e..e933f9c65d904 100644 --- a/fs/notify/fdinfo.c +++ b/fs/notify/fdinfo.c @@ -47,10 +47,8 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode) size = f->handle_bytes >> 2;
ret = exportfs_encode_fid(inode, (struct fid *)f->f_handle, &size);
if ((ret == FILEID_INVALID) || (ret < 0)) {WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
if ((ret == FILEID_INVALID) || (ret < 0)) return;
} f->handle_type = ret; f->handle_bytes = size * sizeof(u32);diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 3601ddfeddc2e..56eee9f23ea9a 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -442,9 +442,8 @@ struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real, buflen = (dwords << 2);
err = -EIO;
if (WARN_ON(fh_type < 0) ||WARN_ON(buflen > MAX_HANDLE_SZ) ||WARN_ON(fh_type == FILEID_INVALID))
if (fh_type < 0 || fh_type == FILEID_INVALID ||WARN_ON(buflen > MAX_HANDLE_SZ)) goto out_err; fh->fb.version = OVL_FH_VERSION;-- 2.34.1
On Thu, 19 Dec 2024 12:53:01 +0100, Amir Goldstein wrote:
Encoding file handles is usually performed by a filesystem >encode_fh() method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and name_to_handle_at(2) syscall are ready to cope with the possibility of failure to encode a file handle.
[...]
Applied to the vfs.fixes branch of the vfs/vfs.git tree. Patches in the vfs.fixes branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs.fixes
[1/1] fs: relax assertions on failure to encode file handles https://git.kernel.org/vfs/vfs/c/974e3fe0ac61
On Thu 19-12-24 12:53:01, Amir Goldstein wrote:
Encoding file handles is usually performed by a filesystem >encode_fh() method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and name_to_handle_at(2) syscall are ready to cope with the possibility of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that currently have a WARN_ON() assertion when ->encode_fh() fails. Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") in v6.6 as the regressing commit, but this is not accurate.
The aforementioned commit only increases the chances of the assertion and allows triggering the assertion with the reproducer using overlayfs, inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and other reasons of ->encode_fh() failures and more particularly, it was also possible with the exact same reproducer using overlayfs that is mounted with options index=on,nfs_export=on also on kernels < v6.6. Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@googl... Reported-by: Dmitry Safonov dima@arista.com Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F... Cc: stable@vger.kernel.org Signed-off-by: Amir Goldstein amir73il@gmail.com
Yeah, looks sensible. Feel free to add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
Christian,
I could have sumbitted two independant patches to relax the assertion in fsnotify and overlayfs via fsnotify and overlayfs trees, but the nature of the problem is the same and in both cases, the problem became worse with the introduction of non-decodable file handles support, so decided to fix them together and ask you to take the fix via the vfs tree.
Please let you if you think it should be done differently.
Thanks, Amir.
fs/notify/fdinfo.c | 4 +--- fs/overlayfs/copy_up.c | 5 ++--- 2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c index dec553034027e..e933f9c65d904 100644 --- a/fs/notify/fdinfo.c +++ b/fs/notify/fdinfo.c @@ -47,10 +47,8 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode) size = f->handle_bytes >> 2; ret = exportfs_encode_fid(inode, (struct fid *)f->f_handle, &size);
- if ((ret == FILEID_INVALID) || (ret < 0)) {
WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
- if ((ret == FILEID_INVALID) || (ret < 0)) return;
- }
f->handle_type = ret; f->handle_bytes = size * sizeof(u32); diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 3601ddfeddc2e..56eee9f23ea9a 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -442,9 +442,8 @@ struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real, buflen = (dwords << 2); err = -EIO;
- if (WARN_ON(fh_type < 0) ||
WARN_ON(buflen > MAX_HANDLE_SZ) ||WARN_ON(fh_type == FILEID_INVALID))
- if (fh_type < 0 || fh_type == FILEID_INVALID ||
WARN_ON(buflen > MAX_HANDLE_SZ))fh->fb.version = OVL_FH_VERSION; -- 2.34.1
linux-stable-mirror@lists.linaro.org
-
Amir Goldstein -
Christian Brauner -
Jan Kara