floppy: Add an extra bound check on ioctl arguments
commit2886a8bdfa007053b414ab01741a98c18c376a85
authorArjan van de Ven <arjan@infradead.org>
Tue, 15 Dec 2009 02:00:11 +0000 (14 18:00 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 15 Dec 2009 16:53:25 +0000 (15 08:53 -0800)
tree6b3d10c16393da65f271fe7865feb4bae97e7674
parentfaa7b7ddca14887ac037f585d2fac7ca6c57037e
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