Merge tag 'probes-fixes-v6.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probe fixes from Masami Hiramatsu:

 - fprobe: Add a comment why fprobe will be skipped if another kprobe is
   running in fprobe_kprobe_handler().

 - probe-events: Fix some issues related to fetch-arguments:

    - Fix double counting of the string length for user-string and
      symstr. This will require longer buffer in the array case.

    - Fix not to count error code (minus value) for the total used
      length in array argument. This makes the total used length
      shorter.

    - Fix to update dynamic used data size counter only if fetcharg uses
      the dynamic size data. This may mis-count the used dynamic data
      size and corrupt data.

    - Revert "tracing: Add "(fault)" name injection to kernel probes"
      because that did not work correctly with a bug, and we agreed the
      current '(fault)' output (instead of '"(fault)"' like a string)
      explains what happened more clearly.

    - Fix to record 0-length (means fault access) data_loc data in fetch
      function itself, instead of store_trace_args(). If we record an
      array of string, this will fix to save fault access data on each
      entry of the array correctly.

* tag 'probes-fixes-v6.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails
  Revert "tracing: Add "(fault)" name injection to kernel probes"
  tracing/probes: Fix to update dynamic data counter if fetcharg uses it
  tracing/probes: Fix not to count error code to total length
  tracing/probes: Fix to avoid double count of the string length on the array
  fprobes: Add a comment why fprobe_kprobe_handler exits if kprobe is running

1 files changed, 8 insertions, 22 deletions

diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h
index c4e1d4c03a85..bb723eefd7b7 100644
--- a/kernel/trace/trace_probe_kernel.h
+++ b/kernel/trace/trace_probe_kernel.h
@@ -2,8 +2,6 @@
 #ifndef __TRACE_PROBE_KERNEL_H_
 #define __TRACE_PROBE_KERNEL_H_
 
-#define FAULT_STRING "(fault)"
-
 /*
  * This depends on trace_probe.h, but can not include it due to
  * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
@@ -15,16 +13,8 @@ static nokprobe_inline int
 fetch_store_strlen_user(unsigned long addr)
 {
 	const void __user *uaddr =  (__force const void __user *)addr;
-	int ret;
 
-	ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
-	/*
-	 * strnlen_user_nofault returns zero on fault, insert the
-	 * FAULT_STRING when that occurs.
-	 */
-	if (ret <= 0)
-		return strlen(FAULT_STRING) + 1;
-	return ret;
+	return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
 }
 
 /* Return the length of string -- including null terminal byte */
@@ -44,18 +34,14 @@ fetch_store_strlen(unsigned long addr)
 		len++;
 	} while (c && ret == 0 && len < MAX_STRING_SIZE);
 
-	/* For faults, return enough to hold the FAULT_STRING */
-	return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
+	return (ret < 0) ? ret : len;
 }
 
-static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
+static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base)
 {
-	if (ret >= 0) {
-		*(u32 *)dest = make_data_loc(ret, __dest - base);
-	} else {
-		strscpy(__dest, FAULT_STRING, len);
-		ret = strlen(__dest) + 1;
-	}
+	if (ret < 0)
+		ret = 0;
+	*(u32 *)dest = make_data_loc(ret, __dest - base);
 }
 
 /*
@@ -76,7 +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);
-	set_data_loc(ret, dest, __dest, base, maxlen);
+	set_data_loc(ret, dest, __dest, base);
 
 	return ret;
 }
@@ -107,7 +93,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
 	 * probing.
 	 */
 	ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
-	set_data_loc(ret, dest, __dest, base, maxlen);
+	set_data_loc(ret, dest, __dest, base);
 
 	return ret;
 }