On Wed, Nov 05, 2025 at 09:06:43AM -0800, Gustavo Luiz Duarte wrote:
> Refactor send_fragmented_body() to use separate offset tracking for
> msgbody, and extradata instead of complex conditional logic.
> The previous implementation used boolean flags and calculated offsets
> which made the code harder to follow.
>
> The new implementation maintains independent offset counters
> (msgbody_offset, extradata_offset) and processes each section
> sequentially, making the data flow more straightforward and the code
> easier to maintain.
>
> This is a preparatory refactoring with no functional changes, which will
> allow easily splitting extradata_complete into separate userdata and
> sysdata buffers in the next patch.
>
> Signed-off-by: Gustavo Luiz Duarte <[email protected]>
> ---
> drivers/net/netconsole.c | 73
> ++++++++++++++++--------------------------------
> 1 file changed, 24 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index 5d8d0214786c..0a8ba7c4bc9d 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -1553,13 +1553,16 @@ static void send_fragmented_body(struct
> netconsole_target *nt,
> const char *msgbody, int header_len,
> int msgbody_len, int extradata_len)
> {
> - int sent_extradata, preceding_bytes;
> const char *extradata = NULL;
> int body_len, offset = 0;
> + int extradata_offset = 0;
> + int msgbody_offset = 0;
>
> #ifdef CONFIG_NETCONSOLE_DYNAMIC
> extradata = nt->extradata_complete;
> #endif
extradata could be NULL at this time if CONFIG_NETCONSOLE_DYNAMIC is
unset. Basically extradata=NULL will not be replaced.
> + if (WARN_ON_ONCE(!extradata && extradata_len != 0))
> + return;
And entradata_len = 0 for CONFIG_NETCONSOLE_DYNAMIC disabled.
> + /* write msgbody first */
> + this_chunk = min(msgbody_len - msgbody_offset,
> + MAX_PRINT_CHUNK - this_header);
> + memcpy(nt->buf + this_header, msgbody + msgbody_offset,
> + this_chunk);
> + msgbody_offset += this_chunk;
> + this_offset += this_chunk;
> +
> + /* after msgbody, append extradata */
> + this_chunk = min(extradata_len - extradata_offset,
> + MAX_PRINT_CHUNK - this_header - this_offset);
> + memcpy(nt->buf + this_header + this_offset,
> + extradata + extradata_offset, this_chunk);
then you are going to memcpy from NULL pointer (`extradata + extradata_offset`
== 0).
I got this my vim LSP that printed:
Null pointer passed as 2nd argument to memory copy function
[unix.cstring.NullArg]
