We could calculate max_aces based on a minimum sized ace and maximum smb frame size (which would be 64K presumably for Windows for non-Writes, but larger for Samba), but not sure if it is worth the trouble unless you find a path where we would parse beyond end of frame, On Wed, Jan 11, 2012 at 12:20 PM, Jeff Layton <jlayton@xxxxxxxxx> wrote: > On Wed, 11 Jan 2012 11:24:03 -0600 > Steve French <smfrench@xxxxxxxxx> wrote: > >> On Wed, Jan 11, 2012 at 9:50 AM, Shirish Pargaonkar >> <shirishpargaonkar@xxxxxxxxx> wrote: >> > On Wed, Jan 11, 2012 at 1:46 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: >> >> On 32 bit systems num_aces * sizeof(struct cifs_ace *) could overflow >> >> leading to a smaller ppace buffer than we expected. >> >> >> >> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> >> >> >> >> diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c >> >> index 72ddf23..c1b2544 100644 >> >> --- a/fs/cifs/cifsacl.c >> >> +++ b/fs/cifs/cifsacl.c >> >> @@ -909,6 +909,8 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl, >> >> umode_t group_mask = S_IRWXG; >> >> umode_t other_mask = S_IRWXU | S_IRWXG | S_IRWXO; >> >> >> >> + if (num_aces > ULONG_MAX / sizeof(struct cifs_ace *)) >> > >> > Should an error/warning (like cifs client can't handle these many aces or >> > possible erroneous number of aces sent by server etc.) be logged before >> > returning? >> > >> >> + return; >> >> ppace = kmalloc(num_aces * sizeof(struct cifs_ace *), >> >> GFP_KERNEL); >> >> if (!ppace) { >> >> Perhaps. Also note that you would overflow maximum smb size if num >> aces is huge >> so would you have even gotten this far? >> > > Only if the smb frame is properly formed. It's possible that it's > corrupt in such a way that the num_aces field is much larger than it > should be, but the rest of the frame looks OK. > > -- > Jeff Layton <jlayton@xxxxxxxxx> -- Thanks, Steve -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html