From 45bc25843ee4c5c6183b6fba013fba1e11eb05b1 Mon Sep 17 00:00:00 2001 From: Ian Schram Date: Fri, 18 Sep 2009 21:26:26 +0200 Subject: [PATCH] perf_counter: Fix perf_copy_attr() pointer arithmetic commit cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba upstream. There is still some weird code in per_copy_attr(). Which supposedly checks that all bytes trailing a struct are zero. It doesn't seem to get pointer arithmetic right. Since it increments an iterating pointer by sizeof(unsigned long) rather than 1. Signed-off-by: Ian Schram [ v2: clean up the messy PTR_ALIGN logic as well. ] Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker LKML-Reference: <4AB3DEE2.3030600@telenet.be> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/perf_counter.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 3f49f5393564..b1dc4684e66a 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -4143,8 +4143,8 @@ done: static int perf_copy_attr(struct perf_counter_attr __user *uattr, struct perf_counter_attr *attr) { - int ret; u32 size; + int ret; if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0)) return -EFAULT; @@ -4169,19 +4169,19 @@ static int perf_copy_attr(struct perf_counter_attr __user *uattr, /* * If we're handed a bigger struct than we know of, - * ensure all the unknown bits are 0. + * ensure all the unknown bits are 0 - i.e. new + * user-space does not rely on any kernel feature + * extensions we dont know about yet. */ if (size > sizeof(*attr)) { - unsigned long val; - unsigned long __user *addr; - unsigned long __user *end; + unsigned char __user *addr; + unsigned char __user *end; + unsigned char val; - addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr), - sizeof(unsigned long)); - end = PTR_ALIGN((void __user *)uattr + size, - sizeof(unsigned long)); + addr = (void __user *)uattr + sizeof(*attr); + end = (void __user *)uattr + size; - for (; addr < end; addr += sizeof(unsigned long)) { + for (; addr < end; addr++) { ret = get_user(val, addr); if (ret) return ret; -- 2.39.5