From: Thomas Gleixner Date: Mon, 11 Nov 2019 22:03:15 +0000 (+0100) Subject: x86/ptrace: Prevent truncation of bitmap size X-Git-Tag: v5.15~5074^2~21 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8c40397f22a4ff7996d3abdc2d9d1d90f9fc8054;p=platform%2Fkernel%2Flinux-starfive.git x86/ptrace: Prevent truncation of bitmap size The active() callback of the IO bitmap regset divides the IO bitmap size by the word size (32/64 bit). As the I/O bitmap size is in bytes the active check fails for bitmap sizes of 1-3 bytes on 32bit and 1-7 bytes on 64bit. Use DIV_ROUND_UP() instead. Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Reviewed-by: Andy Lutomirski --- diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 3c5bbe8..7c52674 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -697,7 +697,7 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n, static int ioperm_active(struct task_struct *target, const struct user_regset *regset) { - return target->thread.io_bitmap_max / regset->size; + return DIV_ROUND_UP(target->thread.io_bitmap_max, regset->size); } static int ioperm_get(struct task_struct *target,