[PATCH] perf_counter: fix buffer overflow in perf_copy_attr()

[PATCH] perf_counter: fix buffer overflow in perf_copy_attr()

[Xiao Guangrong]

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 make kernel unsafe and no-root user can trigger it.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 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 667ab25..75c46c0 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -4216,6 +4216,7 @@ 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);
-- 
1.6.1.2

Re: [PATCH] perf_counter: fix buffer overflow in perf_copy_attr()

[Paul Mackerras]

Xiao Guangrong writes:

> 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 make kernel unsafe and no-root user can trigger it.
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
>  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 667ab25..75c46c0 100644
> --- a/kernel/perf_counter.c
> +++ b/kernel/perf_counter.c
> @@ -4216,6 +4216,7 @@ static int perf_copy_attr(struct perf_counter_attr __user *uattr,
>  			if (val)
>  				goto err_size;
>  		}
> +		size = sizeof(*attr);

Looks right to me.

Acked-by: Paul Mackerras <paulus@samba.org>

Re: [PATCH] perf_counter: fix buffer overflow in perf_copy_attr()

[Peter Zijlstra]

On Tue, 2009-09-15 at 14:44 +0800, Xiao Guangrong wrote:
> 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 make kernel unsafe and no-root user can trigger it.

Ah, indeed. Thanks!

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
>  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 667ab25..75c46c0 100644
> --- a/kernel/perf_counter.c
> +++ b/kernel/perf_counter.c
> @@ -4216,6 +4216,7 @@ 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);

[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@cn.fujitsu.com>
AuthorDate: Tue, 15 Sep 2009 14:44:36 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
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@cn.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul Mackerras <paulus@samba.org>
Cc: <stable@kernel.org>
LKML-Reference: <4AAF37D4.5010706@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 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);