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SubjectRe: [PATCH] drivers/edac/edac_mc: Remove all strcpy() uses
On 25.07.21 18:29:54, Len Baker wrote:
> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. The safe replacement is strscpy().
>
> However, to add labels is better to use the scnprintf to simplify the
> arithmetic.
>
> This is a previous step in the path to remove the strcpy() function
> entirely from the kernel.
>
> Signed-off-by: Len Baker <len.baker@gmx.com>
> ---
> This is a task of the KSPP [1]
>
> [1] https://github.com/KSPP/linux/issues/88
>
> drivers/edac/edac_mc.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
> index f6d462d0be2d..1286364f0e48 100644
> --- a/drivers/edac/edac_mc.c
> +++ b/drivers/edac/edac_mc.c
> @@ -1027,6 +1027,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
> {
> struct dimm_info *dimm;
> char *p;
> + size_t p_size = 0;

I would rather use a 'left' variable which is initialized with
sizeof(e->label) close to there p = e->label is.

> int row = -1, chan = -1;
> int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer };
> int i, n_labels = 0;
> @@ -1113,12 +1114,11 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
> p = e->label;
> *p = '\0';
> } else {
> - if (p != e->label) {
> - strcpy(p, OTHER_LABEL);
> - p += strlen(OTHER_LABEL);
> - }
> - strcpy(p, dimm->label);
> - p += strlen(p);
> + const char *or = (p != e->label) ? OTHER_LABEL : "";
> +
> + p_size += scnprintf(p + p_size,
> + sizeof(e->label) - p_size,
> + "%s%s", or, dimm->label);

My preference is to advance p here (and decrement 'left'). This is the
pattern how p is used throughout the code. I also don't see a benefit
of using scnprintf() here compared to the previous implementation.

Thanks,

-Robert

> }
>
> /*
> @@ -1140,9 +1140,9 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
> }
>
> if (any_memory)
> - strcpy(e->label, "any memory");
> + strscpy(e->label, "any memory", sizeof(e->label));
> else if (!*e->label)
> - strcpy(e->label, "unknown memory");
> + strscpy(e->label, "unknown memory", sizeof(e->label));
>
> edac_inc_csrow(e, row, chan);
>
> --
> 2.25.1
>

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