From: sk b <[EMAIL PROTECTED]> Date: Wed, 16 May 2007 22:56:22 -0600 > 3: if (!access_ok(VERIFY_READ,stp,sizeof(struct st))) > 4: return; > 5: if (!access_ok(VERIFY_WRITE,stp->u,sizeof(int))) > 6: return;
This code would not exist in the kernel, the kernel cannot dereference stp->u. The stp->u dereference would silently work on x86 and x86_64 but it would generate an exception on sparc64 and other platforms. User space accesses must go through the proper copy_from_user(), copy_to_user, get_user(), and put_user() interfaces. It must first copy stp into a local kernel space copy, then it may inspect the value of stp->u. And yes sparse would catch this problem in your code, because the "__user" annotations would catch the illegal "stp->u" dereference. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
