* [PATCH] NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds
@ 2021-03-02 0:19 Randy Dunlap
2021-03-16 22:35 ` Randy Dunlap
0 siblings, 1 reply; 3+ messages in thread
From: Randy Dunlap @ 2021-03-02 0:19 UTC (permalink / raw)
To: linux-kernel
Cc: Randy Dunlap, syzbot+ba2e91df8f74809417fa,
syzbot+f3a0fa110fd630ab56c8, Trond Myklebust, Anna Schumaker,
linux-nfs, David Howells, Al Viro, stable
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)
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds
2021-03-02 0:19 [PATCH] NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds Randy Dunlap
@ 2021-03-16 22:35 ` Randy Dunlap
2021-03-16 23:19 ` Trond Myklebust
0 siblings, 1 reply; 3+ messages in thread
From: Randy Dunlap @ 2021-03-16 22:35 UTC (permalink / raw)
To: linux-kernel
Cc: syzbot+ba2e91df8f74809417fa, syzbot+f3a0fa110fd630ab56c8,
Trond Myklebust, Anna Schumaker, linux-nfs, David Howells,
Al Viro, stable
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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds
2021-03-16 22:35 ` Randy Dunlap
@ 2021-03-16 23:19 ` Trond Myklebust
0 siblings, 0 replies; 3+ messages in thread
From: Trond Myklebust @ 2021-03-16 23:19 UTC (permalink / raw)
To: rdunlap@infradead.org, linux-kernel@vger.kernel.org
Cc: dhowells@redhat.com, linux-nfs@vger.kernel.org,
stable@vger.kernel.org, anna.schumaker@netapp.com,
viro@zeniv.linux.org.uk,
syzbot+ba2e91df8f74809417fa@syzkaller.appspotmail.com,
syzbot+f3a0fa110fd630ab56c8@syzkaller.appspotmail.com
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-03-02 0:19 [PATCH] NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds Randy Dunlap
2021-03-16 22:35 ` Randy Dunlap
2021-03-16 23:19 ` Trond Myklebust
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