Messages in this thread | | | Date | Wed, 26 Nov 2014 09:27:06 -0500 | From | Steven Rostedt <> | Subject | Re: [patch] tracing: off by one in __trace_array_vprintk() |
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On Wed, 26 Nov 2014 17:06:21 +0300 Dan Carpenter <dan.carpenter@oracle.com> wrote:
> This check says "goto out;" if we had to truncate the string. > > The "tbuffer" buffer has TRACE_BUF_SIZE bytes. The vsnprintf() function > returns the number of characters (not counting the NUL char) which would > have been printed if there were space. If we we tried to print > TRACE_BUF_SIZE characters, the last character would have been truncated > to make space for the NUL character so we should "goto out;". >
Oh, and the NUL character is never copied. We copy the string into the buffer with:
memcpy(&entry->buf, tbuffer, len);
Where len does not include NUL, and why we add it ourselves.
-- Steve
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