[PATCH] smbfs: double free memory corruption

smbfs allocates rq_trans2buffer to handle server's multi transaction2 response
messages.  As struct smb_request may be reused, rq_trans2buffer is freed
before each new request.  However if last servers's response is not multi but
single trans2 message then new rq_trans2buffer is not allocated but last
smb_rput still tries to free it again.

To prevent this issue rq_trans2buffer pointer should be set to NULL after
kfree.

Signed-off-by: Vasily Averin <vvs@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/smbfs/request.c b/fs/smbfs/request.c
index 42261dbdf60f172270dff8c70c1942c50a2ce0b3..723f7c6676614f6343ad6d3df7ca850c434eb282 100644 (file)
--- a/fs/smbfs/request.c
+++ b/fs/smbfs/request.c
@@ -181,6 +181,7 @@ static int smb_setup_request(struct smb_request *req)
        req->rq_errno = 0;
        req->rq_fragment = 0;
        kfree(req->rq_trans2buffer);
+       req->rq_trans2buffer = NULL;
 
        return 0;
 }