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* [brauner:pidfd_capabilities 6/7] kernel/fork.c:2743 clone3_args_valid() warn: signedness bug returning '(-22)'
@ 2020-01-25  6:55 ` Dan Carpenter
  0 siblings, 0 replies; 2+ messages in thread
From: Dan Carpenter @ 2020-01-25  6:55 UTC (permalink / raw)
  To: kbuild

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git pidfd_capabilities
head:   39f8e5a5a89ad52ff07fd5af7e514def2b527ed5
commit: aac4bbd536549cbb7440326d09a35ddf9c28f50b [6/7] pidfd: introduce caps

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/fork.c:2743 clone3_args_valid() warn: signedness bug returning '(-22)'
kernel/pid.c:621 __pidfd_fget() error: uninitialized symbol 'oldcred'.

# https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?id=aac4bbd536549cbb7440326d09a35ddf9c28f50b
git remote add brauner https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git
git remote update brauner
git checkout aac4bbd536549cbb7440326d09a35ddf9c28f50b
vim +2743 kernel/fork.c

fa729c4df55893 Christian Brauner 2019-10-31  2721  static bool clone3_args_valid(struct kernel_clone_args *kargs)
                                                          ^^^^

7f192e3cd316ba Christian Brauner 2019-05-25  2722  {
b612e5df4587c9 Christian Brauner 2019-10-14  2723  	/* Verify that no unknown flags are passed along. */
b612e5df4587c9 Christian Brauner 2019-10-14  2724  	if (kargs->flags & ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND))
7f192e3cd316ba Christian Brauner 2019-05-25  2725  		return false;
7f192e3cd316ba Christian Brauner 2019-05-25  2726  
7f192e3cd316ba Christian Brauner 2019-05-25  2727  	/*
7f192e3cd316ba Christian Brauner 2019-05-25  2728  	 * - make the CLONE_DETACHED bit reuseable for clone3
7f192e3cd316ba Christian Brauner 2019-05-25  2729  	 * - make the CSIGNAL bits reuseable for clone3
7f192e3cd316ba Christian Brauner 2019-05-25  2730  	 */
7f192e3cd316ba Christian Brauner 2019-05-25  2731  	if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
7f192e3cd316ba Christian Brauner 2019-05-25  2732  		return false;
7f192e3cd316ba Christian Brauner 2019-05-25  2733  
b612e5df4587c9 Christian Brauner 2019-10-14  2734  	if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
b612e5df4587c9 Christian Brauner 2019-10-14  2735  	    (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
b612e5df4587c9 Christian Brauner 2019-10-14  2736  		return false;
b612e5df4587c9 Christian Brauner 2019-10-14  2737  
7f192e3cd316ba Christian Brauner 2019-05-25  2738  	if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
7f192e3cd316ba Christian Brauner 2019-05-25  2739  	    kargs->exit_signal)
7f192e3cd316ba Christian Brauner 2019-05-25  2740  		return false;
7f192e3cd316ba Christian Brauner 2019-05-25  2741  
aac4bbd536549c Christian Brauner 2020-01-19  2742  	if (kargs->pidfd_flags & ~PIDFD_CAP_GETFD)
aac4bbd536549c Christian Brauner 2020-01-19 @2743  		return -EINVAL;
                                                                ^^^^^^^^^^^^^^

aac4bbd536549c Christian Brauner 2020-01-19  2744  
aac4bbd536549c Christian Brauner 2020-01-19  2745  	if ((kargs->pidfd_flags & PIDFD_CAP_GETFD) &&
aac4bbd536549c Christian Brauner 2020-01-19  2746  	    !ns_capable(current_user_ns(), CAP_SYS_PTRACE))
aac4bbd536549c Christian Brauner 2020-01-19  2747  		return -EPERM;
                                                                ^^^^^^^^^^^^^
This will return true which has security implications.

aac4bbd536549c Christian Brauner 2020-01-19  2748  
fa729c4df55893 Christian Brauner 2019-10-31  2749  	if (!clone3_stack_valid(kargs))
fa729c4df55893 Christian Brauner 2019-10-31  2750  		return false;
fa729c4df55893 Christian Brauner 2019-10-31  2751  
7f192e3cd316ba Christian Brauner 2019-05-25  2752  	return true;
7f192e3cd316ba Christian Brauner 2019-05-25  2753  }

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org Intel Corporation

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2020-01-25  6:55 [brauner:pidfd_capabilities 6/7] kernel/fork.c:2743 clone3_args_valid() warn: signedness bug returning '(-22)' Dan Carpenter
2020-01-25  6:55 ` Dan Carpenter

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