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SubjectRe: [PATCH 5/9] kprobes: Silence DEBUG_STRICT_USER_COPY_CHECKS=y warning
(2011/05/13 8:50), Stephen Boyd wrote:
> Enabling DEBUG_STRICT_USER_COPY_CHECKS causes the following
> warning:
>
> In file included from arch/x86/include/asm/uaccess.h:573,
> from kernel/kprobes.c:55:
> In function 'copy_from_user',
> inlined from 'write_enabled_file_bool' at
> kernel/kprobes.c:2191:
> arch/x86/include/asm/uaccess_64.h:65:
> warning: call to 'copy_from_user_overflow' declared with
> attribute warning: copy_from_user() buffer size is not provably
> correct
>
> presumably due to buf_size being signed causing GCC to fail to
> see that buf_size can't become negative.

Good catch! At least, since the "count" is size_t, buf_size
should be size_t too.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thank you!

>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
> kernel/kprobes.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 7798181..1938187 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2185,7 +2185,7 @@ static ssize_t write_enabled_file_bool(struct file *file,
> const char __user *user_buf, size_t count, loff_t *ppos)
> {
> char buf[32];
> - int buf_size;
> + size_t buf_size;
>
> buf_size = min(count, (sizeof(buf)-1));
> if (copy_from_user(buf, user_buf, buf_size))


--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com


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