From e0a04b11e4059cab033469617c2a3ce2d8cab416 Mon Sep 17 00:00:00 2001 From: Xiaochen Wang Date: Sun, 1 May 2011 11:41:41 +0800 Subject: [PATCH] scripts/kallsyms.c: fix potential segfault Description: This bug hardly appears during real kernel compiling, because the vmlinux symbols table is huge. But we can still catch it under strict condition , as follows. $ echo "c101b97b T do_fork" | ./scripts/kallsyms --all-symbols #include ...... ...... .globl kallsyms_token_table ALGN kallsyms_token_table: Segmentation fault (core dumped) $ If symbols table is small, all entries in token_profit[0x10000] may decrease to 0 after several calls of compress_symbols() in optimize_result(). In that case, find_best_token() always return 0 and best_table[i] is set to "\0\0" and best_table_len[i] is set to 2. As a result, expand_symbol(best_table[0]="\0\0", best_table_len[0]=2, buf) in write_src() will run in infinite recursion until stack overflows, causing segfault. This patch checks the find_best_token() return value. If all entries in token_profit[0x10000] become 0 according to return value, it breaks the loop in optimize_result(). And expand_symbol() works well when best_table_len[i] is 0. Signed-off-by: Xiaochen Wang Acked-by: Paulo Marques Signed-off-by: Michal Marek --- scripts/kallsyms.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 60dd3eb9366..487ac6f37ca 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -500,6 +500,8 @@ static void optimize_result(void) /* find the token with the breates profit value */ best = find_best_token(); + if (token_profit[best] == 0) + break; /* place it in the "best" table */ best_table_len[i] = 2; -- 2.20.1