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authorDmitry Vyukov <dvyukov@google.com>2018-02-06 15:40:28 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-02-25 11:05:42 +0100
commitc33f9272eefe349fed598999943e626fcef8a708 (patch)
tree506d8d2ce82cc9bf6ce2e7b64d20f60b4193a70f /kernel
parent9748fd5ba546bb93d403208d2fd40dd5fc557b6b (diff)
kcov: detect double association with a single task
commit a77660d231f8b3d84fd23ed482e0964f7aa546d6 upstream. Currently KCOV_ENABLE does not check if the current task is already associated with another kcov descriptor. As the result it is possible to associate a single task with more than one kcov descriptor, which later leads to a memory leak of the old descriptor. This relation is really meant to be one-to-one (task has only one back link). Extend validation to detect such misuse. Link: http://lkml.kernel.org/r/20180122082520.15716-1-dvyukov@google.com Fixes: 5c9a8750a640 ("kernel: add kcov code coverage") Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reported-by: Shankara Pailoor <sp3485@columbia.edu> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: syzbot <syzkaller@googlegroups.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kcov.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c
index 3cbb0c879705..3883df58aa12 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -220,9 +220,9 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
if (unused != 0 || kcov->mode == KCOV_MODE_DISABLED ||
kcov->area == NULL)
return -EINVAL;
- if (kcov->t != NULL)
- return -EBUSY;
t = current;
+ if (kcov->t != NULL || t->kcov != NULL)
+ return -EBUSY;
/* Cache in task struct for performance. */
t->kcov_size = kcov->size;
t->kcov_area = kcov->area;