staging: unisys: visorchannel_write() fix potential memory corruption

This fixes the memory corruption case, if nbytes is less than offset
and sizeof(struct channel_header)

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/unisys/visorbus/visorchannel.c b/drivers/staging/unisys/visorbus/visorchannel.c
index b1155ab..20b6349 100644 (file)
--- a/drivers/staging/unisys/visorbus/visorchannel.c
+++ b/drivers/staging/unisys/visorbus/visorchannel.c
@@ -258,7 +258,7 @@ visorchannel_write(struct visorchannel *channel, ulong offset,
                return -EIO;
 
        if (offset < chdr_size) {
-               copy_size = min(chdr_size, nbytes) - offset;
+               copy_size = min(chdr_size - offset, nbytes);
                memcpy(&channel->chan_hdr + offset, local, copy_size);
        }