From f612acfae86af7ecad754ae6a46019be9da05b8e Mon Sep 17 00:00:00 2001
From: YueHaibing <yuehaibing@huawei.com>
Date: Tue Feb 19 10:10:38 2019 +0800
Subject: [PATCH] exec: Fix mem leak in kernel_read_file

Git-commit: f612acfae86af7ecad754ae6a46019be9da05b8e
References: bsc#1126209,CVE-2019-8980
Patch-mainline: v5.1-rc1

syzkaller report this:
Bug: memory leak
unreferenced object 0xffffc9000488d000 (size 9195520):
  comm "syz-executor.0", pid 2752, jiffies 4294787496 (age 18.757s)
  hex dump (first 32 bytes):
    ff ff ff ff ff ff ff ff a8 00 00 00 01 00 00 00  ................
    02 00 00 00 00 00 00 00 80 a1 7a c1 ff ff ff ff  ..........z.....
  backtrace:
    [<000000000863775c>] __vmalloc_node mm/vmalloc.c:1795 [inline]
    [<000000000863775c>] __vmalloc_node_flags mm/vmalloc.c:1809 [inline]
    [<000000000863775c>] vmalloc+0x8c/0xb0 mm/vmalloc.c:1831
    [<000000003f668111>] kernel_read_file+0x58f/0x7d0 fs/exec.c:924
    [<000000002385813f>] kernel_read_file_from_fd+0x49/0x80 fs/exec.c:993
    [<0000000011953ff1>] __do_sys_finit_module+0x13b/0x2a0 kernel/module.c:3895
    [<000000006f58491f>] do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    [<00000000ee78baf4>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<00000000241f889b>] 0xffffffffffffffff

It should goto 'out_free' lable to free allocated buf while kernel_read
fails.

Fixes: 39d637af5aa7 ("vfs: forbid write access when reading a file into memory")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

---
 fs/exec.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index fb72d36..bcf3837 100644

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -943,7 +943,7 @@ int kernel_read_file(struct file *file,
 				    i_size - pos);
 		if (bytes < 0) {
 			ret = bytes;
-			goto out;
+			goto out_free;
 		}
 
 		if (bytes == 0)