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| author | Jann Horn <jannh@google.com> | 2018-07-06 18:12:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-17 12:39:26 +0300 |
| commit | 90f2a76ccd37cce2530df49335bcea6cd0e23797 (patch) | |
| tree | f79c2e257aa853a7b96c0946fafb608447f1b6ab | |
| parent | f24b02c3a0818651f179bdf1026a8de67a97070f (diff) | |
| download | linux-90f2a76ccd37cce2530df49335bcea6cd0e23797.tar.xz | |
USB: yurex: fix out-of-bounds uaccess in read handler
commit f1e255d60ae66a9f672ff9a207ee6cd8e33d2679 upstream.
In general, accessing userspace memory beyond the length of the supplied
buffer in VFS read/write handlers can lead to both kernel memory corruption
(via kernel_read()/kernel_write(), which can e.g. be triggered via
sys_splice()) and privilege escalation inside userspace.
Fix it by using simple_read_from_buffer() instead of custom logic.
Fixes: 6bc235a2e24a ("USB: add driver for Meywa-Denki & Kayac YUREX")
Signed-off-by: Jann Horn <jannh@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/misc/yurex.c | 23 |
1 files changed, 6 insertions, 17 deletions
diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 58abdf28620a..47763311a42e 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -400,8 +400,7 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct usb_yurex *dev; - int retval = 0; - int bytes_read = 0; + int len = 0; char in_buffer[20]; unsigned long flags; @@ -409,26 +408,16 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, mutex_lock(&dev->io_mutex); if (!dev->interface) { /* already disconnected */ - retval = -ENODEV; - goto exit; + mutex_unlock(&dev->io_mutex); + return -ENODEV; } spin_lock_irqsave(&dev->lock, flags); - bytes_read = snprintf(in_buffer, 20, "%lld\n", dev->bbu); + len = snprintf(in_buffer, 20, "%lld\n", dev->bbu); spin_unlock_irqrestore(&dev->lock, flags); - - if (*ppos < bytes_read) { - if (copy_to_user(buffer, in_buffer + *ppos, bytes_read - *ppos)) - retval = -EFAULT; - else { - retval = bytes_read - *ppos; - *ppos += bytes_read; - } - } - -exit: mutex_unlock(&dev->io_mutex); - return retval; + + return simple_read_from_buffer(buffer, count, ppos, in_buffer, len); } static ssize_t yurex_write(struct file *file, const char __user *user_buffer, |