diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2016-01-26 11:29:03 +0100 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-02-15 15:45:28 -0500 |
| commit | 5abd25f01c03b52d8aa39813656782917aa10d9b (patch) | |
| tree | 5216d390ecc2e8b77f3ba83a8fbde202af8ef407 /net | |
| parent | 8448609ec0b8b36759338905a7a5f620555623d8 (diff) | |
| download | linux-exynos-5abd25f01c03b52d8aa39813656782917aa10d9b.tar.gz linux-exynos-5abd25f01c03b52d8aa39813656782917aa10d9b.tar.bz2 linux-exynos-5abd25f01c03b52d8aa39813656782917aa10d9b.zip | |
rfkill: fix rfkill_fop_read wait_event usage
[ Upstream commit 6736fde9672ff6717ac576e9bba2fd5f3dfec822 ]
The code within wait_event_interruptible() is called with
!TASK_RUNNING, so mustn't call any functions that can sleep,
like mutex_lock().
Since we re-check the list_empty() in a loop after the wait,
it's safe to simply use list_empty() without locking.
This bug has existed forever, but was only discovered now
because all userspace implementations, including the default
'rfkill' tool, use poll() or select() to get a readable fd
before attempting to read.
Cc: stable@vger.kernel.org
Fixes: c64fb01627e24 ("rfkill: create useful userspace interface")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/rfkill/core.c | 16 |
1 files changed, 4 insertions, 12 deletions
diff --git a/net/rfkill/core.c b/net/rfkill/core.c index fa7cd792791c..a97bb7332607 100644 --- a/net/rfkill/core.c +++ b/net/rfkill/core.c @@ -1081,17 +1081,6 @@ static unsigned int rfkill_fop_poll(struct file *file, poll_table *wait) return res; } -static bool rfkill_readable(struct rfkill_data *data) -{ - bool r; - - mutex_lock(&data->mtx); - r = !list_empty(&data->events); - mutex_unlock(&data->mtx); - - return r; -} - static ssize_t rfkill_fop_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { @@ -1108,8 +1097,11 @@ static ssize_t rfkill_fop_read(struct file *file, char __user *buf, goto out; } mutex_unlock(&data->mtx); + /* since we re-check and it just compares pointers, + * using !list_empty() without locking isn't a problem + */ ret = wait_event_interruptible(data->read_wait, - rfkill_readable(data)); + !list_empty(&data->events)); mutex_lock(&data->mtx); if (ret) |