NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds

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commit c09f11ef35 upstream.

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: 9954bf92c0 ("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
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Randy Dunlap 2021-03-01 16:19:30 -08:00 • committed by Greg Kroah-Hartman

parent e0f2d86481

commit 96fa26b74c

1 changed files with 12 additions and 0 deletions

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fs/nfs/fs_context.c

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