From: Andrey Konovalov <andreyknvl@google.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Stern <stern@rowland.harvard.edu>,
Andrew Morton <akpm@linux-foundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v3 2/7] kcov: fix potential use-after-free in kcov_remote_start
Date: Thu, 19 Mar 2020 23:11:36 +0100 [thread overview]
Message-ID: <de0d3d30ff90776a2a509cc34c7c1c7521bda125.1584655448.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1584655448.git.andreyknvl@google.com>
From: Andrey Konovalov <andreyknvl@gmail.com>
If vmalloc() fails in kcov_remote_start() we'll access remote->kcov
without holding kcov_remote_lock, so remote might potentially be freed
at that point. Cache kcov pointer in a local variable.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
kernel/kcov.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/kcov.c b/kernel/kcov.c
index f6bd119c9419..cc5900ac2467 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -748,6 +748,7 @@ static const struct file_operations kcov_fops = {
void kcov_remote_start(u64 handle)
{
struct kcov_remote *remote;
+ struct kcov *kcov;
void *area;
struct task_struct *t;
unsigned int size;
@@ -774,16 +775,17 @@ void kcov_remote_start(u64 handle)
spin_unlock(&kcov_remote_lock);
return;
}
+ kcov = remote->kcov;
/* Put in kcov_remote_stop(). */
- kcov_get(remote->kcov);
- t->kcov = remote->kcov;
+ kcov_get(kcov);
+ t->kcov = kcov;
/*
* Read kcov fields before unlock to prevent races with
* KCOV_DISABLE / kcov_remote_reset().
*/
- size = remote->kcov->remote_size;
- mode = remote->kcov->mode;
- sequence = remote->kcov->sequence;
+ size = kcov->remote_size;
+ mode = kcov->mode;
+ sequence = kcov->sequence;
area = kcov_remote_area_get(size);
spin_unlock(&kcov_remote_lock);
@@ -791,7 +793,7 @@ void kcov_remote_start(u64 handle)
area = vmalloc(size * sizeof(unsigned long));
if (!area) {
t->kcov = NULL;
- kcov_put(remote->kcov);
+ kcov_put(kcov);
return;
}
}
--
2.25.1.696.g5e7596f4ac-goog
next prev parent reply other threads:[~2020-03-19 22:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 22:11 [PATCH v3 0/7] kcov: collect coverage from usb soft interrupts Andrey Konovalov
2020-03-17 14:54 ` [PATCH USB] usb: raw_gadget: fix compilation warnings in uapi headers Andrey Konovalov
2020-03-19 22:11 ` Andrey Konovalov
2020-03-19 22:13 ` Andrey Konovalov
2020-03-19 22:11 ` [PATCH v3 1/7] kcov: cleanup debug messages Andrey Konovalov
2020-03-19 22:11 ` Andrey Konovalov [this message]
2020-03-19 22:11 ` [PATCH v3 3/7] kcov: move t->kcov assignments into kcov_start/stop Andrey Konovalov
2020-03-19 22:11 ` [PATCH v3 4/7] kcov: move t->kcov_sequence assignment Andrey Konovalov
2020-03-19 22:11 ` [PATCH v3 5/7] kcov: use t->kcov_mode as enabled indicator Andrey Konovalov
2020-03-19 22:11 ` [PATCH v3 6/7] kcov: collect coverage from interrupts Andrey Konovalov
2020-03-19 22:11 ` [PATCH v3 7/7] usb: core: kcov: collect coverage from usb complete callback Andrey Konovalov
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