The patch titled
Subject: mm/gup: fix null pointer dereference detected by coverity
has been added to the -mm tree. Its filename is
mm-gup-fix-null-pointer-dereference-detected-by-coverity.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-fix-null-pointer-dereference-detected-by-coverity.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-fix-null-pointer-dereference-detected-by-coverity.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Miles Chen <miles.chen@xxxxxxxxxxxx>
Subject: mm/gup: fix null pointer dereference detected by coverity
In fixup_user_fault(), it is possible that unlocked is NULL,
so we should test unlocked before using it.
For example, in arch/arc/kernel/process.c, NULL is passed
to fixup_user_fault().
SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new)
{
...
ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr,
FAULT_FLAG_WRITE, NULL);
...
}
Link: http://lkml.kernel.org/r/20200407095107.1988-1-miles.chen@xxxxxxxxxxxx
Fixes: 4a9e1cda2748 ("mm: bring in additional flag for fixup_user_fault to signal unlock")
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/gup.c~mm-gup-fix-null-pointer-dereference-detected-by-coverity
+++ a/mm/gup.c
@@ -1231,7 +1231,8 @@ retry:
if (ret & VM_FAULT_RETRY) {
down_read(&mm->mmap_sem);
if (!(fault_flags & FAULT_FLAG_TRIED)) {
- *unlocked = true;
+ if (unlocked)
+ *unlocked = true;
fault_flags |= FAULT_FLAG_TRIED;
goto retry;
}
_
Patches currently in -mm which might be from miles.chen@xxxxxxxxxxxx are
mm-gup-fix-null-pointer-dereference-detected-by-coverity.patch
