[PATCH] remember to check return value from __copy_to_user() incdrom_read_cdda_old()

[Jesper Juhl]

Hi,

Here's a patch to ensure that the return value from __copy_to_user() gets 
checked in cdrom_read_cdda_old().
I assume that returning -EFAULT if the copy fails to copy all bytes is an 
appropriate action, but please correct me if I'm wrong.

Signed-off-by: Jesper Juhl <juhl-lkml@xxxxxx>

diff -up linux-2.6.9-rc1-bk13-orig/drivers/cdrom/cdrom.c linux-2.6.9-rc1-bk13/drivers/cdrom/cdrom.c
--- linux-2.6.9-rc1-bk13-orig/drivers/cdrom/cdrom.c	2004-08-24 20:44:01.000000000 +0200
+++ linux-2.6.9-rc1-bk13/drivers/cdrom/cdrom.c	2004-09-06 23:41:20.000000000 +0200
@@ -1959,7 +1959,10 @@ static int cdrom_read_cdda_old(struct cd
 		ret = cdrom_read_block(cdi, &cgc, lba, nr, 1, CD_FRAMESIZE_RAW);
 		if (ret)
 			break;
-		__copy_to_user(ubuf, cgc.buffer, CD_FRAMESIZE_RAW * nr);
+		if (__copy_to_user(ubuf, cgc.buffer, CD_FRAMESIZE_RAW * nr)) {
+			kfree(cgc.buffer);
+			return -EFAULT;
+		}
 		ubuf += CD_FRAMESIZE_RAW * nr;
 		nframes -= nr;
 		lba += nr;



I'm wondering if it would make sense to wrap this branch in unlikely() 
since it should rarely fail...?
I should also mention that I've only compile tested this so far.


--
Jesper Juhl

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