[Crash-utility] [PATCH] crash: fix a segment fault

[Wengang Wang]

There could be something wrong in the symbol name buffer for
a kernel module. That could lead to reading from outside of
"strbuf" in crash util code.

Fix:
Theck the index VS strbuf size and skip that symbol in case of
out of band.

Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>
---
 symbols.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/symbols.c b/symbols.c
index 5d7da6e..0b68ba9 100644
--- a/symbols.c
+++ b/symbols.c
@@ -1965,12 +1965,20 @@ store_module_symbols_v2(ulong total, int mods_installed)
 
 			BZERO(buf1, BUFSIZE);
 
-			if (strbuf) 
-				strcpy(buf1,
-					&strbuf[modsym_name(gpl_syms, modsym, i) - first]);
-			else 
+			if (strbuf) {
+				unsigned long addr = modsym_name(gpl_syms, modsym, i);
+				unsigned long index = addr - first;
+
+				if (index < strbuflen)
+					strncpy(buf1,
+						&strbuf[index], BUFSIZE - 1);
+				else
+					fprintf(fp, "\nWarning: module \"%s\" has invalid address %lx for %dth symbol\n",
+						lm->mod_name, addr, i);
+			} else {
 				read_string(modsym_name(gpl_syms, modsym, i), buf1,
                             		BUFSIZE-1);
+			}
 
                 	if (strlen(buf1)) {
 				st->ext_module_symtable[mcnt].value = 
-- 
2.21.0 (Apple Git-122.2)