Hi Masami,
On Thu, Feb 22, 2018 at 04:45:01PM +0900, Masami Hiramatsu wrote:
> In Documentation/trace/kprobetrace.txt, it says
>
> @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
>
> However, the parser doesn't parse minus offset correctly, since
> commit 2fba0c8867af ("tracing/kprobes: Fix probe offset to be
> unsigned") drops minus ("-") offset support for kprobe probe
> address usage.
>
> This fixes the traceprobe_split_symbol_offset() to parse minus
> offset again with checking the offset range, and add a minus
> offset check in kprobe probe address usage.
>
> Fixes: 2fba0c8867af ("tracing/kprobes: Fix probe offset to be unsigned")
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> ---
> Changes in v2.1:
> - Fix to ensure the offset value is less than LONG_MAX.
> - Fail if the offset is minus when traceprobe_split_symbol_offset()
> is used for the probe address.
> - Add Fixes tag.
> ---
> kernel/trace/trace_kprobe.c | 4 ++--
> kernel/trace/trace_probe.c | 15 ++++++++++-----
> kernel/trace/trace_probe.h | 2 +-
> 3 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 5ce9b8cf7be3..b5b1d8aa47d6 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -667,7 +667,7 @@ static int create_trace_kprobe(int argc, char **argv)
> char *symbol = NULL, *event = NULL, *group = NULL;
> int maxactive = 0;
> char *arg;
> - unsigned long offset = 0;
> + long offset = 0;
> void *addr = NULL;
> char buf[MAX_EVENT_NAME_LEN];
>
> @@ -755,7 +755,7 @@ static int create_trace_kprobe(int argc, char **argv)
> symbol = argv[1];
> /* TODO: support .init module functions */
> ret = traceprobe_split_symbol_offset(symbol, &offset);
> - if (ret) {
> + if (ret || offset < 0) {
> pr_info("Failed to parse either an address or a symbol.\n");
> return ret;
> }
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index d59357308677..ec3856147fdd 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -320,21 +320,26 @@ static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
> }
>
> /* Split symbol and offset. */
> -int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
> +int traceprobe_split_symbol_offset(char *symbol, long *offset)
> {
> + unsigned long ul;
> char *tmp;
> int ret;
>
> if (!offset)
> return -EINVAL;
>
> - tmp = strchr(symbol, '+');
> + tmp = strpbrk(symbol, "+-");
> if (tmp) {
> - /* skip sign because kstrtoul doesn't accept '+' */
> - ret = kstrtoul(tmp + 1, 0, offset);
> + ret = kstrtoul(tmp + 1, 0, &ul);
Why not just using kstrtol() which handles the sign correctly?
Thanks,
Namhyung
> if (ret)
> return ret;
> -
> + if (ul > LONG_MAX)
> + return -E2BIG;
> + if (*tmp == '-')
> + *offset = -ul;
> + else
> + *offset = ul;
> *tmp = '\0';
> } else
> *offset = 0;
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 0745f895f780..75daff22ccea 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -365,7 +365,7 @@ extern int traceprobe_conflict_field_name(const char *name,
> extern void traceprobe_update_arg(struct probe_arg *arg);
> extern void traceprobe_free_probe_arg(struct probe_arg *arg);
>
> -extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset);
> +extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
>
> /* Sum up total data length for dynamic arraies (strings) */
> static nokprobe_inline int
>
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