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Subject[PATCH] cifs: fix incorrect use of list iterator after the loop
The bug is here:
if (!tcon) {
resched = true;

Because the list_for_each_entry() never exits early (without any
break/goto/return inside the loop), the iterator 'ses' after the
loop will always be an pointer to a invalid struct containing the
HEAD (&pserver->smb_ses_list). As a result, the uses of 'ses' above
will lead to a invalid memory access.

The original intention should have been to walk each entry 'ses' in
'&tmp_ses_list', delete '&ses->rlist' and put 'ses'. So fix it with
a list_for_each_entry_safe().

Fixes: 3663c9045f51a ("cifs: check reconnects for channels of active tcons too")
Signed-off-by: Xiaomeng Tong <>
fs/cifs/smb2pdu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 7e7909b1ae11..f82d6fcb5c64 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3858,8 +3858,10 @@ void smb2_reconnect_server(struct work_struct *work)
tcon = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL);
if (!tcon) {
resched = true;
- list_del_init(&ses->rlist);
- cifs_put_smb_ses(ses);
+ list_for_each_entry_safe(ses, ses2, &tmp_ses_list, rlist) {
+ list_del_init(&ses->rlist);
+ cifs_put_smb_ses(ses);
+ }
goto done;

base-commit: 14702b3b2438e2f2d07ae93b5d695c166e5c83d1

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