[tip:perfcounters/urgent] perf_counter: Fix buffer overflow in perf_copy_attr()

[tip-bot for Xiao Guangrong]

Commit-ID:  b3e62e35058fc744ac794611f4e79bcd1c5a4b83
Gitweb:     http://git.kernel.org/tip/b3e62e35058fc744ac794611f4e79bcd1c5a4b83
Author:     Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
AuthorDate: Tue, 15 Sep 2009 14:44:36 +0800
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 15 Sep 2009 09:53:31 +0200

perf_counter: Fix buffer overflow in perf_copy_attr()

If we pass a big size data over perf_counter_open() syscall,
the kernel will copy this data to a small buffer, it will
cause kernel crash.

This bug makes the kernel unsafe and non-root local user can
trigger it.

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Paul Mackerras <paulus@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
LKML-Reference: <4AAF37D4.5010706@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 kernel/perf_counter.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index d7cbc57..a67a1dc 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -4171,6 +4171,7 @@ static int perf_copy_attr(struct perf_counter_attr __user *uattr,
 			if (val)
 				goto err_size;
 		}
+		size = sizeof(*attr);
 	}
 
 	ret = copy_from_user(attr, uattr, size);
--
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