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Re: [Xen-devel] [PATCH v2 1/4] xen/console: Don't treat NUL character as the end of the buffer
- To: Julien Grall <julien.grall@xxxxxxx>
- From: Jan Beulich <JBeulich@xxxxxxxx>
- Date: Thu, 8 Aug 2019 13:51:11 +0000
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Ian Jackson <ian.jackson@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Thu, 08 Aug 2019 14:00:25 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Thread-index: AQHVS5HylAe3eE1UcUur5OQYZ6SMtKbxSYOA
- Thread-topic: [PATCH v2 1/4] xen/console: Don't treat NUL character as the end of the buffer
On 05.08.2019 15:29, Julien Grall wrote:
> @@ -1261,14 +1259,15 @@ void debugtrace_printk(const char *fmt, ...)
> ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
>
> va_start(args, fmt);
> - vsnprintf(buf, sizeof(buf), fmt, args);
> + nr = vscnprintf(buf, sizeof(buf), fmt, args);
> va_end(args);
>
> if ( debugtrace_send_to_console )
> {
> - snprintf(cntbuf, sizeof(cntbuf), "%u ", ++count);
> - serial_puts(sercon_handle, cntbuf);
> - serial_puts(sercon_handle, buf);
> + unsigned int n = snprintf(cntbuf, sizeof(cntbuf), "%u ", ++count);
While - given the size of cntbuf - the difference is mostly
benign, you using vscnprintf() above calls for you also
using scnprintf() here.
> --- a/xen/include/xen/video.h
> +++ b/xen/include/xen/video.h
> @@ -13,11 +13,11 @@
>
> #ifdef CONFIG_VIDEO
> void video_init(void);
> -extern void (*video_puts)(const char *);
> +extern void (*video_puts)(const char *, size_t nr);
> void video_endboot(void);
> #else
> #define video_init() ((void)0)
> -#define video_puts(s) ((void)0)
> +#define video_puts(s, nr) ((void)0)
While I don't think there's overly much risk of "s" getting an
argument with side effects passed, I think that for "nr" the
risk is there. May I ask that you evaluate both here, just in
case?
Preferably with these adjustments
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Jan
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