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SubjectRe: [PATCH] ntb_tool: Fix infinite loop bug when writing spad/peer_spad file
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On Fri, May 27, 2016 at 4:38 PM, Logan Gunthorpe <logang@deltatee.com> wrote:
> If you tried to write two spads in one line, as per the example:
>
> root@peer# echo '0 0x01010101 1 0x7f7f7f7f' > $DBG_DIR/peer_spad
>
> then the CPU would freeze in an infinite loop.
>
> This wasn't immediately obvious but 'pos' was not incrementing the
> buffer, so after reading the second pair of values, 'pos' would once
> again be 3 and it would re-read the second pair of values ad infinitum.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>

Good catch. Thanks Logan.

Acked-by: Allen Hubbe <Allen.Hubbe@emc.com>

> ---
> drivers/ntb/test/ntb_tool.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
> index 6f5dc6c..209ef7c 100644
> --- a/drivers/ntb/test/ntb_tool.c
> +++ b/drivers/ntb/test/ntb_tool.c
> @@ -268,7 +268,7 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
> {
> int spad_idx;
> u32 spad_val;
> - char *buf;
> + char *buf, *buf_ptr;
> int pos, n;
> ssize_t rc;
>
> @@ -288,14 +288,15 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
> }
>
> buf[size] = 0;
> -
> - n = sscanf(buf, "%d %i%n", &spad_idx, &spad_val, &pos);
> + buf_ptr = buf;
> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
> while (n == 2) {
> + buf_ptr += pos;
> rc = spad_write_fn(tc->ntb, spad_idx, spad_val);
> if (rc)
> break;
>
> - n = sscanf(buf + pos, "%d %i%n", &spad_idx, &spad_val, &pos);
> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
> }
>
> if (n < 0)
> --
> 2.1.4

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