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Commit 9438fabb authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

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: default avatarDarren Lavender <dcl@hppine99.gbr.hp.com>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 9d037a77

fs/cifs/cifssmb.c

+2 −1
Original line number Diff line number Diff line
@@ -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");