From 835d0c737a7e04f30b3990249ce461999ea2cf3a Mon Sep 17 00:00:00 2001
From: Solomon Peachy <pizza@shaftnet.org>
Date: Fri, 6 Aug 2021 09:56:22 -0400
Subject: [PATCH] logf:  Fix two issues with logf_panic_dump()

 * It had a (read) buffer overflow when dumping the stuff on the back half of the buffer
 * a highly questionable code construct was nuked

Change-Id: I7f6f119524fc2095f788fc9b3d356459955d3ace
---
 firmware/export/logf.h |  2 +-
 firmware/logf.c        | 11 ++++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/firmware/export/logf.h b/firmware/export/logf.h
index c8aaad06b4..7fbe5976a4 100644
--- a/firmware/export/logf.h
+++ b/firmware/export/logf.h
@@ -31,7 +31,7 @@
 
 #define MAX_LOGF_SIZE 16384
 
-extern unsigned char logfbuffer[MAX_LOGF_SIZE];
+extern unsigned char logfbuffer[MAX_LOGF_SIZE + 1];
 extern int logfindex;
 extern bool logfwrap;
 extern bool logfenabled;
diff --git a/firmware/logf.c b/firmware/logf.c
index 11ffa4e15c..e71425f2c3 100644
--- a/firmware/logf.c
+++ b/firmware/logf.c
@@ -61,7 +61,7 @@ static int logdiskfindex;
 #ifdef ROCKBOX_HAS_LOGF
 
 #ifndef __PCTOOL__
-unsigned char logfbuffer[MAX_LOGF_SIZE];
+unsigned char logfbuffer[MAX_LOGF_SIZE + 1];
 int logfindex;
 bool logfwrap;
 bool logfenabled = true;
@@ -272,10 +272,14 @@ void logf_panic_dump(int *y)
         return;
     }
 
+    /* Explicitly null-terminate our buffer */
+    logfbuffer[MAX_LOGF_SIZE] = 0;
+
     lcd_puts(1, (*y)++, "start of logf data");
     lcd_update();
-    i = logfindex - 2; /* The last actual characer (i.e. not '\0') */
 
+    /* The intent is to dump the newest log entries first! */
+    i = logfindex - 2; /* The last actual characer (i.e. not '\0') */
     while(i >= 0)
     {
         while(logfbuffer[i] != 0 && i>=0)
@@ -300,12 +304,13 @@ void logf_panic_dump(int *y)
             }
             if(strlen( &logfbuffer[i + 1]) > 0)
             {
-                lcd_putsf(1, (*y)++, "%*s", (MAX_LOGF_SIZE-i) &logfbuffer[i + 1]);
+                lcd_putsf(1, (*y)++, "%*s", &logfbuffer[i + 1]);
                 lcd_update();
             }
         }
         i--;
     }
+
     lcd_puts(1, (*y)++, "end of logf data");
     lcd_update();
 }