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Subject[PATCH 1/4] tracing: probeevent: Fix to support minus offset from symbol
From: Masami Hiramatsu <mhiramat@kernel.org>

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.

Link: http://lkml.kernel.org/r/152129028983.31874.13419301530285775521.stgit@devbox

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Fixes: 2fba0c8867af ("tracing/kprobes: Fix probe offset to be unsigned")
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 4 ++--
kernel/trace/trace_probe.c | 8 +++-----
kernel/trace/trace_probe.h | 2 +-
3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1fad24acd444..ae4147eaebd4 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -659,7 +659,7 @@ 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];

@@ -747,7 +747,7 @@ 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 || offset > UINT_MAX) {
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..daf54bda4dc8 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -320,7 +320,7 @@ 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)
{
char *tmp;
int ret;
@@ -328,13 +328,11 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
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 = kstrtol(tmp, 0, offset);
if (ret)
return ret;
-
*tmp = '\0';
} else
*offset = 0;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index e101c5bb9eda..6a4d3fa94042 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
--
2.15.1

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