[tip:perfcounters/core] perf_counter: Fix perf_copy_attr() pointer arithmetic
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From: tip-bot for Ian Schram on 19 Sep 2009 14:10 Commit-ID: cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba Gitweb: http://git.kernel.org/tip/cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba Author: Ian Schram <ischram(a)telenet.be> AuthorDate: Fri, 18 Sep 2009 21:26:26 +0200 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Sat, 19 Sep 2009 19:32:55 +0200 perf_counter: Fix perf_copy_attr() pointer arithmetic 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 <ischram(a)telenet.be> [ v2: clean up the messy PTR_ALIGN logic as well. ] Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Paul Mackerras <paulus(a)samba.org> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com> Cc: Frederic Weisbecker <fweisbec(a)gmail.com> Cc: <stable(a)kernel.org> # for v2.6.31.x LKML-Reference: <4AB3DEE2.3030600(a)telenet.be> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- kernel/perf_counter.c | 20 ++++++++++---------- 1 files changed, 10 insertions(+), 10 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index d5899b6..cc768ab 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -4208,8 +4208,8 @@ 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; @@ -4234,19 +4234,19 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |