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Re: [PATCH v4 2/9] virtiofsd: Fix breakage due to fuse_init_in size chan
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v4 2/9] virtiofsd: Fix breakage due to fuse_init_in size change |
Date: |
Thu, 27 Jan 2022 17:17:38 +0000 |
User-agent: |
Mutt/2.1.5 (2021-12-30) |
* Vivek Goyal (vgoyal@redhat.com) wrote:
> Kernel version 5.17 has increased the size of "struct fuse_init_in" struct.
> Previously this struct was 16 bytes and now it has been extended to
> 64 bytes in size.
>
> Once qemu headers are updated to latest, it will expect to receive 64 byte
> size struct (for protocol version major 7 and minor > 6). But if guest is
> booting older kernel (older than 5.17), then it still sends older
> fuse_init_in of size 16 bytes. And do_init() fails. It is expecting
> 64 byte struct. And this results in mount of virtiofs failing.
>
> Fix this by parsing 16 bytes only for now. Separate patches will be
> posted which will parse rest of the bytes and enable new functionality.
> Right now we don't support any of the new functionality, so we don't
> lose anything by not parsing bytes beyond 16.
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
OK, I think we should make this 1/9 and get this in quickly; that way
bisect works.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> tools/virtiofsd/fuse_lowlevel.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
> index e4679c73ab..ce29a70253 100644
> --- a/tools/virtiofsd/fuse_lowlevel.c
> +++ b/tools/virtiofsd/fuse_lowlevel.c
> @@ -1880,6 +1880,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
> struct fuse_mbuf_iter *iter)
> {
> size_t compat_size = offsetof(struct fuse_init_in, max_readahead);
> + size_t compat2_size = offsetof(struct fuse_init_in, flags) +
> sizeof(uint32_t);
Yeh so that sizeof() is sizeof the flags, so that's the size of the
sturcture upto and including the flags.
> struct fuse_init_in *arg;
> struct fuse_init_out outarg;
> struct fuse_session *se = req->se;
> @@ -1897,7 +1898,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
>
> /* ...and now consume the new fields. */
> if (arg->major == 7 && arg->minor >= 6) {
> - if (!fuse_mbuf_iter_advance(iter, sizeof(*arg) - compat_size)) {
> + if (!fuse_mbuf_iter_advance(iter, compat2_size - compat_size)) {
> fuse_reply_err(req, EINVAL);
> return;
> }
> --
> 2.31.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- [PATCH v4 0/9] virtiofsd: Add support for file security context at creation, Vivek Goyal, 2022/01/24
- [PATCH v4 5/9] virtiofsd, fuse_lowlevel.c: Add capability to parse security context, Vivek Goyal, 2022/01/24
- [PATCH v4 6/9] virtiofsd: Move core file creation code in separate function, Vivek Goyal, 2022/01/24
- [PATCH v4 2/9] virtiofsd: Fix breakage due to fuse_init_in size change, Vivek Goyal, 2022/01/24
- Re: [PATCH v4 2/9] virtiofsd: Fix breakage due to fuse_init_in size change,
Dr. David Alan Gilbert <=
- [PATCH v4 4/9] virtiofsd: Extend size of fuse_conn_info->capable and ->want fields, Vivek Goyal, 2022/01/24
- [PATCH v4 7/9] virtiofsd: Create new file with fscreate set, Vivek Goyal, 2022/01/24
- [PATCH v4 3/9] virtiofsd: Parse extended "struct fuse_init_in", Vivek Goyal, 2022/01/24
- [PATCH v4 9/9] virtiofsd: Add an option to enable/disable security label, Vivek Goyal, 2022/01/24
- [PATCH v4 8/9] virtiofsd: Create new file using O_TMPFILE and set security context, Vivek Goyal, 2022/01/24
- [PATCH v4 1/9] linux-headers: Update headers to v5.17-rc1, Vivek Goyal, 2022/01/24