Messages in this thread | | | Date | Mon, 17 Oct 2022 09:18:32 +0200 | From | Christian Brauner <> | Subject | Re: [PATCH] copy_process(): fix a memleak in copy_process() |
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On Mon, Oct 17, 2022 at 02:34:06PM +0800, Gaosheng Cui wrote: > 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@huawei.com> > --- > 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);
This will be released during __fput() when ->release() == pidfd_release() is called so calling put_pid() here will result in UAF later on. What syzbot instance does this report come from?
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