The following commit has been merged into the x86/iopl branch of tip: Commit-ID: c5d623b17c2424272b3355a524b094ff02cfd9aa Gitweb: https://git.kernel.org/tip/c5d623b17c2424272b3355a524b094ff02cfd9aa Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Wed, 13 Nov 2019 21:42:41 +01:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Thu, 14 Nov 2019 20:14:59 +01:00 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 <tglx@xxxxxxxxxxxxx> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20191113210103.819769574@xxxxxxxxxxxxx --- arch/x86/kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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,
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