diff options
| author | Randy Dunlap | 2021-03-01 16:19:30 -0800 |
|---|---|---|
| committer | Trond Myklebust | 2021-04-05 09:04:20 -0400 |
| commit | c09f11ef35955785f92369e25819bf0629df2e59 (patch) | |
| tree | db4dd00b82d079280c7e335d688337cdfdf3003c /fs/nfs | |
| parent | f892c41c14e0fa3d78ce37de1d5c8161ed13bf08 (diff) | |
NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds
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
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'fs/nfs')
| -rw-r--r-- | fs/nfs/fs_context.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c index 971a9251c1d9..902db1262d2b 100644 --- a/fs/nfs/fs_context.c +++ b/fs/nfs/fs_context.c @@ -974,6 +974,15 @@ static int nfs23_parse_monolithic(struct fs_context *fc, 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) |