Subject: + drivers-cdrom-cdromc-use-kzalloc-for-failing-hardware.patch added to -mm tree To: jonathan.salwan@xxxxxxxxx,axboe@xxxxxxxxx,dan.carpenter@xxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Fri, 31 May 2013 14:30:46 -0700 The patch titled Subject: drivers/cdrom/cdrom.c: use kzalloc() for failing hardware has been added to the -mm tree. Its filename is drivers-cdrom-cdromc-use-kzalloc-for-failing-hardware.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Jonathan Salwan <jonathan.salwan@xxxxxxxxx> Subject: drivers/cdrom/cdrom.c: use kzalloc() for failing hardware In drivers/cdrom/cdrom.c mmc_ioctl_cdrom_read_data() allocates a memory area with kmalloc in line 2885. 2885 cgc->buffer = kmalloc(blocksize, GFP_KERNEL); 2886 if (cgc->buffer == NULL) 2887 return -ENOMEM; In line 2908 we can find the copy_to_user function: 2908 if (!ret && copy_to_user(arg, cgc->buffer, blocksize)) The cgc->buffer is never cleaned and initialized before this function. If ret = 0 with the previous basic block, it's possible to display some memory bytes in kernel space from userspace. When we read a block from the disk it normally fills the ->buffer but if the drive is malfunctioning there is a chance that it would only be partially filled. The result is an leak information to userspace. Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/cdrom/cdrom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN drivers/cdrom/cdrom.c~drivers-cdrom-cdromc-use-kzalloc-for-failing-hardware drivers/cdrom/cdrom.c --- a/drivers/cdrom/cdrom.c~drivers-cdrom-cdromc-use-kzalloc-for-failing-hardware +++ a/drivers/cdrom/cdrom.c @@ -2882,7 +2882,7 @@ static noinline int mmc_ioctl_cdrom_read if (lba < 0) return -EINVAL; - cgc->buffer = kmalloc(blocksize, GFP_KERNEL); + cgc->buffer = kzalloc(blocksize, GFP_KERNEL); if (cgc->buffer == NULL) return -ENOMEM; _ Patches currently in -mm which might be from jonathan.salwan@xxxxxxxxx are drivers-cdrom-cdromc-use-kzalloc-for-failing-hardware.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html