From 2886a8bdfa007053b414ab01741a98c18c376a85 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven 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 Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/floppy.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index d41d7f01854..3266b4f65da 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)