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: [email protected]
Reported-by: [email protected]
Signed-off-by: Randy Dunlap <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: [email protected]
Cc: David Howells <[email protected]>
Cc: Al Viro <[email protected]>
Cc: [email protected]
---
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)
