From f569599ae70f0899035f8d5876a7939f629c5976 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 29 Sep 2010 15:27:08 -0400 Subject: [PATCH] cifs: prevent infinite recursion in cifs_reconnect_tcon cifs_reconnect_tcon is called from smb_init. After a successful reconnect, cifs_reconnect_tcon will call reset_cifs_unix_caps. That function will, in turn call CIFSSMBQFSUnixInfo and CIFSSMBSetFSUnixInfo. Those functions also call smb_init. It's possible for the session and tcon reconnect to succeed, and then for another cifs_reconnect to occur before CIFSSMBQFSUnixInfo or CIFSSMBSetFSUnixInfo to be called. That'll cause those functions to call smb_init and cifs_reconnect_tcon again, ad infinitum... Break the infinite recursion by having those functions use a new smb_init variant that doesn't attempt to perform a reconnect. Reported-and-Tested-by: Michal Suchanek Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/cifssmb.c | 49 +++++++++++++++++++++++++++++++---------------- 1 file changed, 33 insertions(+), 16 deletions(-) diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index c65c3419dd37..7e83b356cc9e 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -232,7 +232,7 @@ static int small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, void **request_buf) { - int rc = 0; + int rc; rc = cifs_reconnect_tcon(tcon, smb_command); if (rc) @@ -250,7 +250,7 @@ small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, if (tcon != NULL) cifs_stats_inc(&tcon->num_smbs_sent); - return rc; + return 0; } int @@ -281,16 +281,9 @@ small_smb_init_no_tc(const int smb_command, const int wct, /* If the return code is zero, this function must fill in request_buf pointer */ static int -smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, - void **request_buf /* returned */ , - void **response_buf /* returned */ ) +__smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, + void **request_buf, void **response_buf) { - int rc = 0; - - rc = cifs_reconnect_tcon(tcon, smb_command); - if (rc) - return rc; - *request_buf = cifs_buf_get(); if (*request_buf == NULL) { /* BB should we add a retry in here if not a writepage? */ @@ -309,7 +302,31 @@ smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, if (tcon != NULL) cifs_stats_inc(&tcon->num_smbs_sent); - return rc; + return 0; +} + +/* If the return code is zero, this function must fill in request_buf pointer */ +static int +smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, + void **request_buf, void **response_buf) +{ + int rc; + + rc = cifs_reconnect_tcon(tcon, smb_command); + if (rc) + return rc; + + return __smb_init(smb_command, wct, tcon, request_buf, response_buf); +} + +static int +smb_init_no_reconnect(int smb_command, int wct, struct cifsTconInfo *tcon, + void **request_buf, void **response_buf) +{ + if (tcon->ses->need_reconnect || tcon->need_reconnect) + return -EHOSTDOWN; + + return __smb_init(smb_command, wct, tcon, request_buf, response_buf); } static int validate_t2(struct smb_t2_rsp *pSMB) @@ -4534,8 +4551,8 @@ CIFSSMBQFSUnixInfo(const int xid, struct cifsTconInfo *tcon) cFYI(1, "In QFSUnixInfo"); QFSUnixRetry: - rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB, - (void **) &pSMBr); + rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon, + (void **) &pSMB, (void **) &pSMBr); if (rc) return rc; @@ -4604,8 +4621,8 @@ CIFSSMBSetFSUnixInfo(const int xid, struct cifsTconInfo *tcon, __u64 cap) cFYI(1, "In SETFSUnixInfo"); SETFSUnixRetry: /* BB switch to small buf init to save memory */ - rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB, - (void **) &pSMBr); + rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon, + (void **) &pSMB, (void **) &pSMBr); if (rc) return rc;