Messages in this thread Patch in this message | | | Date | Thu, 01 Oct 2009 18:16:17 -0700 | From | Greg KH <> | Subject | [029/136] perf_counter: Fix perf_copy_attr() pointer arithmetic |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Ian Schram <ischram@telenet.be>
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 <ischram@telenet.be> [ v2: clean up the messy PTR_ALIGN logic as well. ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4AB3DEE2.3030600@telenet.be> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/perf_counter.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)
--- 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_co /* * 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; - - addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr), - sizeof(unsigned long)); - end = PTR_ALIGN((void __user *)uattr + size, - sizeof(unsigned long)); + unsigned char __user *addr; + unsigned char __user *end; + unsigned char val; + + 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;
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