From 2886a8bdfa007053b414ab01741a98c18c376a85 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@infradead.org>
Date: Mon, 14 Dec 2009 18:00:11 -0800
Subject: [PATCH] floppy: Add an extra bound check on ioctl arguments
gcc is not convinced that the floppy.c ioctl has sufficient bound checks:
In function `copy_from_user',
inlined from `fd_copyin' at drivers/block/floppy.c:3080,
inlined from `fd_ioctl' at drivers/block/floppy.c:3503:
arch/x86/include/asm/uaccess_32.h:211:
warning: call to `copy_from_user_overflow' declared with attribute
warning: copy_from_user buffer size is not provably correct
And frankly, as a human I have a hard time proving the same more or less
(the size comes from the ioctl argument. humpf. maybe. the code isn't
very nice)
This patch adds an explicit check to make 100% sure it's safe, better than
finding out later that there indeed was a gap.
[akpm@linux-foundation.org: add WARN_ON()]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/block/floppy.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index d41d7f0185498..3266b4f65daa3 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3497,6 +3497,9 @@ static int fd_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
((cmd & 0x80) && !capable(CAP_SYS_ADMIN)))
return -EPERM;
+ if (WARN_ON(size < 0 || size > sizeof(inparam)))
+ return -EINVAL;
+
/* copyin */
CLEARSTRUCT(&inparam);
if (_IOC_DIR(cmd) & _IOC_WRITE)
--
2.30.2