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Subject[PATCH 5.4 10/98] smb3: Call cifs reconnect from demultiplex thread
Date
From: Rohith Surabattula <rohiths@microsoft.com>

commit de9ac0a6e9efdffc8cde18781f48fb56ca4157b7 upstream.

cifs_reconnect needs to be called only from demultiplex thread.
skip cifs_reconnect in offload thread. So, cifs_reconnect will be
called by demultiplex thread in subsequent request.

These patches address a problem found during decryption offload:
CIFS: VFS: trying to dequeue a deleted mid
that can cause a refcount use after free:

[ 1271.389453] Workqueue: smb3decryptd smb2_decrypt_offload [cifs]
[ 1271.389456] RIP: 0010:refcount_warn_saturate+0xae/0xf0
[ 1271.389457] Code: fa 1d 6a 01 01 e8 c7 44 b1 ff 0f 0b 5d c3 80 3d e7 1d 6a 01 00 75 91 48 c7 c7 d8 be 1d a2 c6 05 d7 1d 6a 01 01 e8 a7 44 b1 ff <0f> 0b 5d c3 80 3d c5 1d 6a 01 00 0f 85 6d ff ff ff 48 c7 c7 30 bf
[ 1271.389458] RSP: 0018:ffffa4cdc1f87e30 EFLAGS: 00010286
[ 1271.389458] RAX: 0000000000000000 RBX: ffff9974d2809f00 RCX: ffff9974df898cc8
[ 1271.389459] RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffff9974df898cc0
[ 1271.389460] RBP: ffffa4cdc1f87e30 R08: 0000000000000004 R09: 00000000000002c0
[ 1271.389460] R10: 0000000000000000 R11: 0000000000000001 R12: ffff9974b7fdb5c0
[ 1271.389461] R13: ffff9974d2809f00 R14: ffff9974ccea0a80 R15: ffff99748e60db80
[ 1271.389462] FS: 0000000000000000(0000) GS:ffff9974df880000(0000) knlGS:0000000000000000
[ 1271.389462] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1271.389463] CR2: 000055c60f344fe4 CR3: 0000001031a3c002 CR4: 00000000003706e0
[ 1271.389465] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1271.389465] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1271.389466] Call Trace:
[ 1271.389483] cifs_mid_q_entry_release+0xce/0x110 [cifs]
[ 1271.389499] smb2_decrypt_offload+0xa9/0x1c0 [cifs]
[ 1271.389501] process_one_work+0x1e8/0x3b0
[ 1271.389503] worker_thread+0x50/0x370
[ 1271.389504] kthread+0x12f/0x150
[ 1271.389506] ? process_one_work+0x3b0/0x3b0
[ 1271.389507] ? __kthread_bind_mask+0x70/0x70
[ 1271.389509] ret_from_fork+0x22/0x30

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org> #5.4+
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/smb2ops.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3979,7 +3979,8 @@ init_read_bvec(struct page **pages, unsi
static int
handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
char *buf, unsigned int buf_len, struct page **pages,
- unsigned int npages, unsigned int page_data_size)
+ unsigned int npages, unsigned int page_data_size,
+ bool is_offloaded)
{
unsigned int data_offset;
unsigned int data_len;
@@ -4001,7 +4002,8 @@ handle_read_data(struct TCP_Server_Info

if (server->ops->is_session_expired &&
server->ops->is_session_expired(buf)) {
- cifs_reconnect(server);
+ if (!is_offloaded)
+ cifs_reconnect(server);
wake_up(&server->response_q);
return -1;
}
@@ -4142,7 +4144,8 @@ static void smb2_decrypt_offload(struct
mid->decrypted = true;
rc = handle_read_data(dw->server, mid, dw->buf,
dw->server->vals->read_rsp_size,
- dw->ppages, dw->npages, dw->len);
+ dw->ppages, dw->npages, dw->len,
+ true);
mid->callback(mid);
cifs_mid_q_entry_release(mid);
}
@@ -4246,7 +4249,7 @@ non_offloaded_decrypt:
(*mid)->decrypted = true;
rc = handle_read_data(server, *mid, buf,
server->vals->read_rsp_size,
- pages, npages, len);
+ pages, npages, len, false);
}

free_pages:
@@ -4391,7 +4394,7 @@ smb3_handle_read_data(struct TCP_Server_
char *buf = server->large_buf ? server->bigbuf : server->smallbuf;

return handle_read_data(server, mid, buf, server->pdu_size,
- NULL, 0, 0);
+ NULL, 0, 0, false);
}

static int

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