A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 03:01:39 -04:00
Code Issues Projects Releases Packages Wiki Activity

ptrace: restore smp_rmb() in __ptrace_may_access()

Browse source 
Restore the read memory barrier in __ptrace_may_access() that was deleted
a couple years ago. Also add comments on this barrier and the one it pairs
with to explain why they're there (as far as I understand).

Fixes: bfedb58925 ("mm: Add a user_ns owner to mm_struct and fix ptrace permission checks")
Cc: [email protected]
Acked-by: Kees Cook <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Signed-off-by: Jann Horn <[email protected]>
Signed-off-by: Eric W. Biederman <[email protected]>
This commit is contained in:
Jann Horn 2019-05-29 13:31:57 +02:00 • committed by Eric W. Biederman
commit f6581f5b55
2 changed files with 19 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

10
kernel/ptrace.c
View file

@ -323,6 +323,16 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
return -EPERM;
ok:
rcu_read_unlock();
/*
* If a task drops privileges and becomes nondumpable (through a syscall
* like setresuid()) while we are trying to access it, we must ensure
* that the dumpability is read after the credentials; otherwise,
* we may be able to attach to a task that we shouldn't be able to
* attach to (as if the task had dropped privileges without becoming
* nondumpable).
* Pairs with a write barrier in commit_creds().
*/
smp_rmb();
mm = task->mm;
if (mm &&
((get_dumpable(mm) != SUID_DUMP_USER) &&