diff options
| author | Dmitry Vyukov <dvyukov@google.com> | 2018-02-06 15:40:28 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 18:32:46 -0800 |
| commit | a77660d231f8b3d84fd23ed482e0964f7aa546d6 (patch) | |
| tree | de3b60669f8ad14825330b0ec2217bb17bb25d23 /kernel/kcov.c | |
| parent | a1be1f3931bfe0a42b46fef77a04593c2b136e7f (diff) | |
| download | lwn-a77660d231f8b3d84fd23ed482e0964f7aa546d6.tar.gz lwn-a77660d231f8b3d84fd23ed482e0964f7aa546d6.zip | |
kcov: detect double association with a single task
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>
Diffstat (limited to 'kernel/kcov.c')
| -rw-r--r-- | kernel/kcov.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c index 7594c033d98a..2c16f1ab5e10 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -358,7 +358,8 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, */ if (kcov->mode != KCOV_MODE_INIT || !kcov->area) return -EINVAL; - if (kcov->t != NULL) + t = current; + if (kcov->t != NULL || t->kcov != NULL) return -EBUSY; if (arg == KCOV_TRACE_PC) kcov->mode = KCOV_MODE_TRACE_PC; @@ -370,7 +371,6 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, #endif else return -EINVAL; - t = current; /* Cache in task struct for performance. */ t->kcov_size = kcov->size; t->kcov_area = kcov->area; |