[PATCH] copy_process(): fix a memleak in copy_process()

From: Gaosheng Cui
Date: Mon Oct 17 2022 - 02:34:23 EST


If CLONE_PIDFD is set in clone_flags, pidfile will hold the reference
count of pid by getpid(pid), In the error path bad_fork_put_pidfd, the
reference of pid needs to be released, otherwise there will be a
memleak issue, fix it.

unreferenced object 0xffff888164aed400 (size 224):
comm "sh", pid 75274, jiffies 4295717290 (age 2955.536s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
backtrace:
[<00000000bcb9eebb>] kmem_cache_alloc+0x16a/0x7f0
[<00000000340cf9ad>] alloc_pid+0xc5/0xce0
[<000000002387362c>] copy_process+0x29ef/0x6c90
[<00000000bf7d7efc>] kernel_clone+0xd9/0xc70
[<0000000047b1a04f>] __do_sys_clone+0xe1/0x120
[<0000000000f1aa25>] __x64_sys_clone+0xc3/0x150
[<00000000250a19f1>] do_syscall_64+0x5c/0x90
[<000000007e0ac417>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 6fd2fe494b17 ("copy_process(): don't use ksys_close() on cleanups")
Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
---
kernel/fork.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index 08969f5aa38d..8706c06be8af 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2499,6 +2499,7 @@ static __latent_entropy struct task_struct *copy_process(
cgroup_cancel_fork(p, args);
bad_fork_put_pidfd:
if (clone_flags & CLONE_PIDFD) {
+ put_pid(pid);
fput(pidfile);
put_unused_fd(pidfd);
}
--
2.25.1