diff options
author | Pavel Shilovsky <pshilov@microsoft.com> | 2019-01-18 17:25:36 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-31 08:13:44 +0100 |
commit | 2cffcebe17439fab6d2d54d754054cd3da547f09 (patch) | |
tree | 009ea553574c12a78463f6baa5643600e3f3617f /fs/cifs/smb2ops.c | |
parent | 1c69ba8b1453eb1c9f77536433616dab0a147c65 (diff) |
CIFS: Do not reconnect TCP session in add_credits()
commit ef68e831840c40c7d01b328b3c0f5d8c4796c232 upstream.
When executing add_credits() we currently call cifs_reconnect()
if the number of credits is zero and there are no requests in
flight. In this case we may call cifs_reconnect() recursively
twice and cause memory corruption given the following sequence
of functions:
mid1.callback() -> add_credits() -> cifs_reconnect() ->
-> mid2.callback() -> add_credits() -> cifs_reconnect().
Fix this by avoiding to call cifs_reconnect() in add_credits()
and checking for zero credits in the demultiplex thread.
Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/cifs/smb2ops.c')
-rw-r--r-- | fs/cifs/smb2ops.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 05548379fbb7..fb1c65f93114 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -33,6 +33,7 @@ #include "smb2glob.h" #include "cifs_ioctl.h" +/* Change credits for different ops and return the total number of credits */ static int change_conf(struct TCP_Server_Info *server) { @@ -40,17 +41,15 @@ change_conf(struct TCP_Server_Info *server) server->oplock_credits = server->echo_credits = 0; switch (server->credits) { case 0: - return -1; + return 0; case 1: server->echoes = false; server->oplocks = false; - cifs_dbg(VFS, "disabling echoes and oplocks\n"); break; case 2: server->echoes = true; server->oplocks = false; server->echo_credits = 1; - cifs_dbg(FYI, "disabling oplocks\n"); break; default: server->echoes = true; @@ -63,14 +62,15 @@ change_conf(struct TCP_Server_Info *server) server->echo_credits = 1; } server->credits -= server->echo_credits + server->oplock_credits; - return 0; + return server->credits + server->echo_credits + server->oplock_credits; } static void smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add, const int optype) { - int *val, rc = 0; + int *val, rc = -1; + spin_lock(&server->req_lock); val = server->ops->get_credits_field(server, optype); *val += add; @@ -94,8 +94,26 @@ smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add, } spin_unlock(&server->req_lock); wake_up(&server->request_q); - if (rc) - cifs_reconnect(server); + + if (server->tcpStatus == CifsNeedReconnect) + return; + + switch (rc) { + case -1: + /* change_conf hasn't been executed */ + break; + case 0: + cifs_dbg(VFS, "Possible client or server bug - zero credits\n"); + break; + case 1: + cifs_dbg(VFS, "disabling echoes and oplocks\n"); + break; + case 2: + cifs_dbg(FYI, "disabling oplocks\n"); + break; + default: + cifs_dbg(FYI, "add %u credits total=%d\n", add, rc); + } } static void |