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[1/3] tracing/probes: Fix to avoid double count of the string length on the array

Message ID 168830923752.2278819.12200306485001986374.stgit@mhiramat.roam.corp.google.com (mailing list archive)
State Superseded
Headers show
Series tracing/probes: Fix bugs in process_fetch_insn | expand

Commit Message

Masami Hiramatsu (Google) July 2, 2023, 2:47 p.m. UTC 
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

If an array is specified with the ustring or symstr, the length of the
strings are accumlated on both of 'ret' and 'total', which means the
length is double counted.
Just set the length to the 'ret' value to aviod double count.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/8819b154-2ba1-43c3-98a2-cbde20892023@moroto.mountain/
Fixes: 88903c464321 ("tracing/probe: Add ustring type for user-space string")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe_tmpl.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Masami Hiramatsu (Google) July 3, 2023, 8:21 a.m. UTC | #1 
On Sun, 2 Jul 2023 17:44:38 +0200
Markus Elfring <Markus.Elfring@web.de> wrote:

> …
> > Just set the length to the 'ret' value to aviod double count.
> 
> Would the wording “… avoid double counting” be more appropriate
> for a subsequent change description?

Yeah, thanks!

> 
> Regards,
> Markus
diff mbox series

Patch

diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 00707630788d..4735c5cb76fa 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -156,11 +156,11 @@  process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 			code++;
 			goto array;
 		case FETCH_OP_ST_USTRING:
-			ret += fetch_store_strlen_user(val + code->offset);
+			ret = fetch_store_strlen_user(val + code->offset);
 			code++;
 			goto array;
 		case FETCH_OP_ST_SYMSTR:
-			ret += fetch_store_symstrlen(val + code->offset);
+			ret = fetch_store_symstrlen(val + code->offset);
 			code++;
 			goto array;
 		default: