diff options
| author | Jiri Slaby <jslaby@suse.cz> | 2015-11-27 16:50:43 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-17 09:35:28 +0100 |
| commit | 6f61bd5c4ff5c2b6a63113bff6c4a4bace2b9a3a (patch) | |
| tree | ddc6c77c2dc9f24fa0d790584a044d183c7bc913 /drivers/char | |
| parent | f065b5f78d17fe835ad6f51f1a4f8e3e2e0efec3 (diff) | |
hwrng: core - sleep interruptible in read
commit 1ab87298cb59b649d8d648d25dc15b36ab865f5a upstream.
hwrng kthread can be waiting via hwrng_fillfn for some data from a rng
like virtio-rng:
hwrng D ffff880093e17798 0 382 2 0x00000000
...
Call Trace:
[<ffffffff817339c6>] wait_for_completion_killable+0x96/0x210
[<ffffffffa00aa1b7>] virtio_read+0x57/0xf0 [virtio_rng]
[<ffffffff814f4a35>] hwrng_fillfn+0x75/0x130
[<ffffffff810aa243>] kthread+0xf3/0x110
And when some user program tries to read the /dev node in this state,
we get:
rngd D ffff880093e17798 0 762 1 0x00000004
...
Call Trace:
[<ffffffff817351ac>] mutex_lock_nested+0x15c/0x3e0
[<ffffffff814f478e>] rng_dev_read+0x6e/0x240
[<ffffffff81231958>] __vfs_read+0x28/0xe0
[<ffffffff81232393>] vfs_read+0x83/0x130
And this is indeed unkillable. So use mutex_lock_interruptible
instead of mutex_lock in rng_dev_read and exit immediatelly when
interrupted. And possibly return already read data, if any (as POSIX
allows).
v2: use ERESTARTSYS instead of EINTR
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: <linux-crypto@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/hw_random/core.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index cf25020576fa..340f96e44642 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -238,7 +238,10 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, goto out; } - mutex_lock(&reading_mutex); + if (mutex_lock_interruptible(&reading_mutex)) { + err = -ERESTARTSYS; + goto out_put; + } if (!data_avail) { bytes_read = rng_get_data(rng, rng_buffer, rng_buffer_size(), @@ -288,6 +291,7 @@ out: out_unlock_reading: mutex_unlock(&reading_mutex); +out_put: put_rng(rng); goto out; } |