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| author | Kent Yoder <key@linux.vnet.ibm.com> | 2012-07-25 21:14:02 +0200 |
|---|---|---|
| committer | Kent Yoder <key@linux.vnet.ibm.com> | 2012-08-22 18:11:49 +0200 |
| commit | dd7da132f7f04f34074efd134847a818ea29ddd7 (patch) | |
| tree | 79448a7b8ccfb8531fbec1f241a853b2b911baa9 /drivers/char | |
| parent | hw_random: add support for the TPM chip as a hardware RNG source (diff) | |
| download | linux-dd7da132f7f04f34074efd134847a818ea29ddd7.tar.xz linux-dd7da132f7f04f34074efd134847a818ea29ddd7.zip | |
tpm: fix double write race and tpm_release free issue
Moved the atomic_set of the data_pending variable until after the
tpm_read has completed processing. The existing code had a window of
time where a second write to the driver could clobber the tpm command
buffer.
Also fixed an issue where if close was called on the tpm device before a
read completed, the tpm command buffer would be returned to the OS,
which could contain sensitive information.
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/tpm/tpm.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c index 36e43e50dcef..0a75638e3e56 100644 --- a/drivers/char/tpm/tpm.c +++ b/drivers/char/tpm/tpm.c @@ -1171,7 +1171,7 @@ int tpm_release(struct inode *inode, struct file *file) flush_work_sync(&chip->work); file->private_data = NULL; atomic_set(&chip->data_pending, 0); - kfree(chip->data_buffer); + kzfree(chip->data_buffer); clear_bit(0, &chip->is_open); put_device(chip->dev); return 0; @@ -1223,7 +1223,6 @@ ssize_t tpm_read(struct file *file, char __user *buf, del_singleshot_timer_sync(&chip->user_read_timer); flush_work_sync(&chip->work); ret_size = atomic_read(&chip->data_pending); - atomic_set(&chip->data_pending, 0); if (ret_size > 0) { /* relay data */ ssize_t orig_ret_size = ret_size; if (size < ret_size) @@ -1238,6 +1237,8 @@ ssize_t tpm_read(struct file *file, char __user *buf, mutex_unlock(&chip->buffer_mutex); } + atomic_set(&chip->data_pending, 0); + return ret_size; } EXPORT_SYMBOL_GPL(tpm_read); |