4.14-stable review patch. If anyone has any objections, please let me know.
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From: Alexey Dobriyan adobriyan@gmail.com
[ Upstream commit 2e0ad552f5f8cd0fda02bc45fcd2b89821c62fd1 ]
task_dump_owner() has the following code:
mm = task->mm; if (mm) { if (get_dumpable(mm) != SUID_DUMP_USER) { uid = ... } }
Check for ->mm is buggy -- kernel thread might be borrowing mm and inode will go to some random uid:gid pair.
Link: http://lkml.kernel.org/r/20180412220109.GA20978@avx2 Signed-off-by: Alexey Dobriyan adobriyan@gmail.com Cc: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/proc/base.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1694,6 +1694,12 @@ void task_dump_owner(struct task_struct kuid_t uid; kgid_t gid;
+ if (unlikely(task->flags & PF_KTHREAD)) { + *ruid = GLOBAL_ROOT_UID; + *rgid = GLOBAL_ROOT_GID; + return; + } + /* Default to the tasks effective ownership */ rcu_read_lock(); cred = __task_cred(task);