[PATCH v4 4/4] tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2023-07-11 02:12:07
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fix to record 0-length data to data_loc in fetch_store_string*() if it fails
to get the string data.
Currently those expect that the data_loc is updated by store_trace_args() if
it returns the error code. However, that does not work correctly if the
argument is an array of strings. In that case, store_trace_args() only clears
the first entry of the array (which may have no error) and leaves other
entries. So it should be cleared by fetch_store_string*() itself.
Also, 'dyndata' and 'maxlen' in store_trace_args() should be updated
only if it is used (ret > 0 and argument is a dynamic data.)
Fixes: 40b53b771806 ("tracing: probeevent: Add array type support")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v4:
- Simplify the updating data_loc code with set_data_loc().
---
kernel/trace/trace_probe_kernel.h | 13 +++++++++----
kernel/trace/trace_probe_tmpl.h | 4 +---
kernel/trace/trace_uprobe.c | 3 ++-
3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h
index 6deae2ce34f8..bb723eefd7b7 100644
--- a/kernel/trace/trace_probe_kernel.h
+++ b/kernel/trace/trace_probe_kernel.h@@ -37,6 +37,13 @@ fetch_store_strlen(unsigned long addr) return (ret < 0) ? ret : len; } +static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base) +{ + if (ret < 0) + ret = 0; + *(u32 *)dest = make_data_loc(ret, __dest - base); +} + /* * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf * with max length and relative data location.
@@ -55,8 +62,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base) __dest = get_loc_data(dest, base); ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base); return ret; }
@@ -87,8 +93,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) * probing. */ ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base); return ret; }
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index ed9d57c6b041..bbad0503f166 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h@@ -267,9 +267,7 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec, if (unlikely(arg->dynamic)) *dl = make_data_loc(maxlen, dyndata - base); ret = process_fetch_insn(arg->code, rec, dl, base); - if (unlikely(ret < 0 && arg->dynamic)) { - *dl = make_data_loc(0, dyndata - base); - } else { + if (unlikely(ret > 0 && arg->dynamic)) { dyndata += ret; maxlen -= ret; }
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 8b92e34ff0c8..7b47e9a2c010 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c@@ -170,7 +170,8 @@ fetch_store_string(unsigned long addr, void *dest, void *base) */ ret++; *(u32 *)dest = make_data_loc(ret, (void *)dst - base); - } + } else + *(u32 *)dest = make_data_loc(0, (void *)dst - base); return ret; }