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| author | Ian Schram <ischram@telenet.be> | 2009-09-18 21:26:26 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-19 19:32:55 +0200 |
| commit | cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba (patch) | |
| tree | c5b68d4ded3b82a934c7bd25d798b8b3870e5b25 /kernel/perf_counter.c | |
| parent | ec60a3fe478c0fc6d109eb5840b435ecee4d132b (diff) | |
| download | lwn-cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba.tar.gz lwn-cdf8073d6b2c6c5a3cd6ce0e6c1297157f7f99ba.zip | |
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@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>
Cc: <stable@kernel.org> # for v2.6.31.x
LKML-Reference: <4AB3DEE2.3030600@telenet.be>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
| -rw-r--r-- | 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 d5899b62b276..cc768ab81ac8 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; |