[PATCH 5.0 46/46] exec: Fix mem leak in kernel_read_file

Greg Kroah-Hartman
2019-03-08T12:53:03Z

From: YueHaibing <yuehaibing@huawei.com>

commit f612acfae86af7ecad754ae6a46019be9da05b8e upstream.

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>
Cc: Thibaut Sautereau <thibaut@sautereau.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -932,7 +932,7 @@ int kernel_read_file(struct file *file,
bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
if (bytes < 0) {
ret = bytes;
- goto out;
+ goto out_free;
}

if (bytes == 0)