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| author | Dmitry Vyukov <dvyukov@google.com> | 2018-02-06 15:40:28 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-25 11:07:50 +0100 |
| commit | 4249e8af8108afadc6316d9e4815f3333c9770d0 (patch) | |
| tree | 41cb9bbada830d7d4dd19c007386a72797b68ad3 | |
| parent | 7b5ec5505945ee2ba6f6dbab51483a1102720623 (diff) | |
| download | linux-stable-4249e8af8108afadc6316d9e4815f3333c9770d0.tar.gz linux-stable-4249e8af8108afadc6316d9e4815f3333c9770d0.tar.bz2 linux-stable-4249e8af8108afadc6316d9e4815f3333c9770d0.zip | |
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>
| -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 fc6af9e1308b..b11ef6e51f7e 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -225,9 +225,9 @@ 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; |