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authorRandy Dunlap2021-03-01 16:19:30 -0800
committerTrond Myklebust2021-04-05 09:04:20 -0400
commitc09f11ef35955785f92369e25819bf0629df2e59 (patch)
treedb4dd00b82d079280c7e335d688337cdfdf3003c /fs/nfs
parentf892c41c14e0fa3d78ce37de1d5c8161ed13bf08 (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.c12
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)