Re: [PATCH] block/compat_ioctl: fix range check in BLKGETSIZE
From: Bart Van Assche
Date: Sat Apr 09 2022 - 17:35:39 EST
On 4/8/22 16:47, Khazhismel Kumykov wrote:
kernel ulong and compat_ulong_t may not be same width. Use type directly
to eliminate mismatches.
This would result in truncation rather than EFBIG for 32bit mode for
large disks.
Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
---
block/ioctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Noticed this one was sitting in my "not landed yet" pile, third time's
the charm? :)
diff --git a/block/ioctl.c b/block/ioctl.c
index 4a86340133e4..959e93a90b29 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -629,7 +629,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
return compat_put_long(argp,
(bdev->bd_disk->bdi->ra_pages * PAGE_SIZE) / 512);
case BLKGETSIZE:
- if (bdev_nr_sectors(bdev) > ~0UL)
+ if (bdev_nr_sectors(bdev) > ~((compat_ulong_t)0UL))
return -EFBIG;
return compat_put_ulong(argp, bdev_nr_sectors(bdev));
A nit: the "UL" and two parentheses can be left out. Anyway:
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>