linux-kernel - [PATCH] fixdep: free memory on second error path of do_config

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Date:   Thu, 14 Dec 2017 20:54:10 +0100
From:   Lukas Bulwahn <lukas.bulwahn@...il.com>
To:     linux-kbuild@...r.kernel.org
Cc:     Alexey Dobriyan <adobriyan@...il.com>, lukas.bulwahn@...il.com,
        sil2review@...ts.osadl.org,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] fixdep: free memory on second error path of do_config_file

Commit dee81e988674 ("fixdep: faster CONFIG_ search") introduces the memory
leak when `map = mmap(...)` was replaced with `map = malloc(...)` and
`read(fd, map, ...)`. It introduces a new second error path, which does not
free the allocated memory for `map`. We now correct that behavior and free
`map` before the do_config_file() function returns.

Facebook's static analysis tool Infer (http://fbinfer.com) found this
memory leak:

  scripts/basic/fixdep.c:297: error: MEMORY_LEAK
    memory dynamically allocated by call to `malloc()` at line 290, \
    column 8 is not reachable after line 297, column 3.

Fixes: dee81e988674 ("fixdep: faster CONFIG_ search")

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
---
 scripts/basic/fixdep.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index bbf62cb..131c450 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -296,6 +296,7 @@ static void do_config_file(const char *filename)
 	if (read(fd, map, st.st_size) != st.st_size) {
 		perror("fixdep: read");
 		close(fd);
+		free(map);
 		return;
 	}
 	map[st.st_size] = '\0';
-- 
2.7.4