| Message ID | 20210302001930.2253-1-rdunlap@infradead.org |
|---|---|
| State | Accepted |
| Commit | c09f11ef35955785f92369e25819bf0629df2e59 |
| Headers | show |
| Series | NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds | expand |
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+ba2e91df8f74809417fa@syzkaller.appspotmail.com > Reported-by: syzbot+f3a0fa110fd630ab56c8@syzkaller.appspotmail.com > Signed-off-by: Randy Dunlap <rdunlap@infradead.org> > Cc: Trond Myklebust <trond.myklebust@hammerspace.com> > Cc: Anna Schumaker <anna.schumaker@netapp.com> > Cc: linux-nfs@vger.kernel.org > Cc: David Howells <dhowells@redhat.com> > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: stable@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
Hi Randy, On Tue, 2021-03-16 at 15:35 -0700, Randy Dunlap wrote: > ping? > I can take this patch for the next merge window. > 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+ba2e91df8f74809417fa@syzkaller.appspotmail.com > > Reported-by: syzbot+f3a0fa110fd630ab56c8@syzkaller.appspotmail.com > > Signed-off-by: Randy Dunlap <rdunlap@infradead.org> > > Cc: Trond Myklebust <trond.myklebust@hammerspace.com> > > Cc: Anna Schumaker <anna.schumaker@netapp.com> > > Cc: linux-nfs@vger.kernel.org > > Cc: David Howells <dhowells@redhat.com> > > Cc: Al Viro <viro@zeniv.linux.org.uk> > > Cc: stable@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) > > > > -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@hammerspace.com
--- 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)
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+ba2e91df8f74809417fa@syzkaller.appspotmail.com Reported-by: syzbot+f3a0fa110fd630ab56c8@syzkaller.appspotmail.com Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Cc: linux-nfs@vger.kernel.org Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org --- fs/nfs/fs_context.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)