Bug: After mounting the cifs fs, it complains with Resource temporarily unavailable messages.

[root@vm1 xfstests-dev]# ./check -g quick -s smb3 TEST_DEV=//<SERVER_IP>/TEST is mounted but not a type cifs filesystem [root@vm1 xfstests-dev]# df df: /mnt/test: Resource temporarily unavailable

Paul's analysis of the bug:

Bug is related to an off-by-one in smb2_set_next_command() when the client attempts to pad SMB2_QUERY_INFO request -- since it isn't 8 byte aligned -- even though smb2_query_info_compound() doesn't provide an extra iov for such padding.

v5.15.y doesn't have

eb3e28c1e89b ("smb3: Replace smb2pdu 1-element arrays with flex-arrays")

and the commit does

if (unlikely(check_add_overflow(input_len, sizeof(*req), &len) || len > CIFSMaxBufSize)) return -EINVAL;

so sizeof(*req) will wrongly include the extra byte from smb2_query_info_req::Buffer making @len unaligned and therefore causing OOB in smb2_set_next_command().

Fixes: bfd18c0f570e4 ("smb: client: fix OOB in SMB2_query_info_init()") Suggested-by: Paulo Alcantara pc@manguebit.com Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com --- This patch is only for 5.15.y stable kernel. I have tested the patched kernel: after mounting it doesn't become unavailable. --- fs/cifs/smb2pdu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 6714e9db0ee83..b4b1d8132910c 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -3448,7 +3448,7 @@ SMB2_query_info_init(struct cifs_tcon *tcon, struct TCP_Server_Info *server,

iov[0].iov_base = (char *)req; /* 1 for Buffer */ - iov[0].iov_len = len; + iov[0].iov_len = len - 1; return 0; }