From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andreas Ziegler <andreas.ziegler@fau.de>,
Masami Hiramatsu <mhiramat@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/3] tracing: uprobes: Re-enable $comm support for uprobe events
Date: Tue, 7 May 2019 22:55:41 +0900 [thread overview]
Message-ID: <155723734162.9149.4042756162201097965.stgit@devnote2> (raw)
In-Reply-To: <155723732200.9149.10482668315693777743.stgit@devnote2>
Since commit 533059281ee5 ("tracing: probeevent: Introduce new
argument fetching code") dropped the $comm support from uprobe
events, this re-enables it.
For $comm support, uses strlcpy() instead of strncpy_from_user()
to copy current task's comm. Because it is in the kernel space,
strncpy_from_user() always fails to copy the comm.
This also uses strlen() instead of strnlen_user() to measure the
length of the comm.
Note that this uses -ECOMM as a token value to fetch the comm
string. If the user-space pointer points -ECOMM, it will be
translated to task->comm.
Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Andreas Ziegler <andreas.ziegler@fau.de>
Acked-by: Andreas Ziegler <andreas.ziegler@fau.de>
---
Changes in v3
- Always add +1 to strlen() result.
- Use -ECOMM as a token to specify current->comm.
---
kernel/trace/trace_probe.h | 1 +
kernel/trace/trace_uprobe.c | 13 +++++++++++--
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index b7737666c1a8..f9a8c632188b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -124,6 +124,7 @@ struct fetch_insn {
/* fetch + deref*N + store + mod + end <= 16, this allows N=12, enough */
#define FETCH_INSN_MAX 16
+#define FETCH_TOKEN_COMM (-ECOMM)
/* Fetch type information table */
struct fetch_type {
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index cd8750a72768..eb7e06b54741 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -156,7 +156,10 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
if (unlikely(!maxlen))
return -ENOMEM;
- ret = strncpy_from_user(dst, src, maxlen);
+ if (addr == FETCH_TOKEN_COMM)
+ ret = strlcpy(dst, current->comm, maxlen);
+ else
+ ret = strncpy_from_user(dst, src, maxlen);
if (ret >= 0) {
if (ret == maxlen)
dst[ret - 1] = '\0';
@@ -180,7 +183,10 @@ fetch_store_strlen(unsigned long addr)
int len;
void __user *vaddr = (void __force __user *) addr;
- len = strnlen_user(vaddr, MAX_STRING_SIZE);
+ if (addr == FETCH_TOKEN_COMM)
+ len = strlen(current->comm) + 1;
+ else
+ len = strnlen_user(vaddr, MAX_STRING_SIZE);
return (len > MAX_STRING_SIZE) ? 0 : len;
}
@@ -220,6 +226,9 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
case FETCH_OP_IMM:
val = code->immediate;
break;
+ case FETCH_OP_COMM:
+ val = FETCH_TOKEN_COMM;
+ break;
case FETCH_OP_FOFFS:
val = translate_user_vaddr(code->immediate);
break;
next prev parent reply other threads:[~2019-05-07 13:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-07 13:55 [PATCH v3 0/3] tracing: probeevent: Fix probe argument parser and handler Masami Hiramatsu
2019-05-07 13:55 ` Masami Hiramatsu [this message]
2019-05-07 13:55 ` [PATCH v3 2/3] tracing: probeevent: Do not accumulate on ret variable Masami Hiramatsu
2019-05-07 13:56 ` [PATCH v3 3/3] tracing: probeevent: Fix to make the type of $comm string Masami Hiramatsu
2019-05-08 2:10 ` [PATCH v3 0/3] tracing: probeevent: Fix probe argument parser and handler Steven Rostedt
2019-05-08 4:59 ` Masami Hiramatsu
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