ping? On 3/1/21 4:19 PM, Randy Dunlap wrote: > Fix shift out-of-bounds in xprt_calc_majortimeo(). This is caused > by a garbage timeout (retrans) mount option being passed to nfs mount, > in this case from syzkaller. > > If the protocol is XPRT_TRANSPORT_UDP, then 'retrans' is a shift > value for a 64-bit long integer, so 'retrans' cannot be >= 64. > If it is >= 64, fail the mount and return an error. > > Fixes: 9954bf92c0cd ("NFS: Move mount parameterisation bits into their own > file") > Reported-by: syzbot+ba2e91df8f7480941...@syzkaller.appspotmail.com > Reported-by: syzbot+f3a0fa110fd630ab5...@syzkaller.appspotmail.com > Signed-off-by: Randy Dunlap <rdun...@infradead.org> > Cc: Trond Myklebust <trond.mykleb...@hammerspace.com> > Cc: Anna Schumaker <anna.schuma...@netapp.com> > Cc: linux-...@vger.kernel.org > Cc: David Howells <dhowe...@redhat.com> > Cc: Al Viro <v...@zeniv.linux.org.uk> > Cc: sta...@vger.kernel.org > --- > fs/nfs/fs_context.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > --- lnx-512-rc1.orig/fs/nfs/fs_context.c > +++ lnx-512-rc1/fs/nfs/fs_context.c > @@ -974,6 +974,15 @@ static int nfs23_parse_monolithic(struct > sizeof(mntfh->data) - mntfh->size); > > /* > + * for proto == XPRT_TRANSPORT_UDP, which is what uses > + * to_exponential, implying shift: limit the shift value > + * to BITS_PER_LONG (majortimeo is unsigned long) > + */ > + if (!(data->flags & NFS_MOUNT_TCP)) /* this will be UDP */ > + if (data->retrans >= 64) /* shift value is too large */ > + goto out_invalid_data; > + > + /* > * Translate to nfs_fs_context, which nfs_fill_super > * can deal with. > */ > @@ -1073,6 +1082,9 @@ out_no_address: > > out_invalid_fh: > return nfs_invalf(fc, "NFS: invalid root filehandle"); > + > +out_invalid_data: > + return nfs_invalf(fc, "NFS: invalid binary mount data"); > } > > #if IS_ENABLED(CONFIG_NFS_V4) >
-- ~Randy