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cifs: fix possible memory corruption in CIFSFindNext

The name_len variable in CIFSFindNext is a signed int that gets set to
the resume_name_len in the cifs_search_info. The resume_name_len however
is unsigned and for some infolevels is populated directly from a 32 bit
value sent by the server.

If the server sends a very large value for this, then that value could
look negative when converted to a signed int. That would make that
value pass the PATH_MAX check later in CIFSFindNext. The name_len would
then be used as a length value for a memcpy. It would then be treated
as unsigned again, and the memcpy scribbles over a ton of memory.

Fix this by making the name_len an unsigned value in CIFSFindNext.

Cc: <stable@kernel.org>
Reported-by: Darren Lavender <dcl@hppine99.gbr.hp.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
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jtlayton authored and Steve French committed Aug 23, 2011
1 parent 9d037a7 commit 9438fabb73eb48055b58b89fc51e0bc4db22fabd
Showing with 2 additions and 1 deletion.
  1. +2 −1 fs/cifs/cifssmb.c
@@ -4079,7 +4079,8 @@ int CIFSFindNext(const int xid, struct cifs_tcon *tcon,
T2_FNEXT_RSP_PARMS *parms;
char *response_data;
int rc = 0;
int bytes_returned, name_len;
int bytes_returned;
unsigned int name_len;
__u16 params, byte_count;

cFYI(1, "In FindNext");

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