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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>
This commit is contained in:
Jeff Layton 2011-08-23 07:21:28 -04:00 committed by Steve French
parent 9d037a7776
commit 9438fabb73
1 changed files with 2 additions and 1 deletions
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3
fs/cifs/cifssmb.c
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@ -4079,7 +4079,8 @@ int CIFSFindNext(const int xid, struct cifs_tcon *tcon,
T2_FNEXT_RSP_PARMS *parms; T2_FNEXT_RSP_PARMS *parms;
char *response_data; char *response_data;
int rc = 0; int rc = 0;
int bytes_returned, name_len; int bytes_returned;
unsigned int name_len;
__u16 params, byte_count; __u16 params, byte_count;
cFYI(1, "In FindNext"); cFYI(1, "In FindNext");