Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 034/159] kcov: detect double association with a single task | Date | Fri, 23 Feb 2018 19:25:42 +0100 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Vyukov <dvyukov@google.com>
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>
--- kernel/kcov.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -225,9 +225,9 @@ static int kcov_ioctl_locked(struct kcov 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;
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