| Date | Fri, 15 Nov 2019 21:12:30 -0000 | From | "tip-bot2 for Thomas Gleixner" <> | Subject | [tip: x86/iopl] x86/ptrace: Prevent truncation of bitmap size |
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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@linutronix.de> AuthorDate: Wed, 13 Nov 2019 21:42:41 +01:00 Committer: Thomas Gleixner <tglx@linutronix.de> 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@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191113210103.819769574@linutronix.de
--- 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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