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| author | Xiao Han <xiao.han@orange.fr> | 2016-06-14 16:22:54 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-09 15:45:59 +0200 |
| commit | 9c6256a5e707a9eb8b91962b550050b13aa75334 (patch) | |
| tree | bfd9bd5a35e7648fffe2353e36259b50cb0369cd | |
| parent | usb: misc: usbtest: usbtest_do_ioctl may return positive integer (diff) | |
| download | linux-9c6256a5e707a9eb8b91962b550050b13aa75334.tar.xz linux-9c6256a5e707a9eb8b91962b550050b13aa75334.zip | |
usb: misc: ftdi-elan: Fix off-by-one memory corruptions
This patch fixes fives off-by-one bugs in the ftdi-elan driver code. The
bug can be triggered by plugging a USB adapter for CardBus 3G cards (model
U132 manufactured by Elan Digital Systems, Ltd), causing a kernel panic.
The fix was tested on Ubuntu 14.04.4 with 4.7.0-rc14.2.0-27-generic+ and
4.4.0-22-generic+ kernel. In the ftdi_elan_synchronize function, an
off-by-one memory corruption occurs when packet_bytes is equal or bigger
than m. After having read m bytes, that is bytes_read is equal to m, "
..\x00" is still copied to the stack variable causing an out bounds write
of 4 bytes, which overwrites the stack canary and results in a kernel
panic.
This off-by-one requires physical access to the machine. It is not
exploitable since we have no control on the overwritten data. Similar
off-by-one bugs have been observed in 4 other functions:
ftdi_elan_stuck_waiting, ftdi_elan_read, ftdi_elan_edset_output and
ftdi_elan_flush_input_fifo.
Reported-by: Alex Palesandro <palexster@gmail.com>
Signed-off-by: Xiao Han <xiao.han@orange.fr>
Tested-by: Paul Chaignon <pchaigno@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/misc/ftdi-elan.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/usb/misc/ftdi-elan.c b/drivers/usb/misc/ftdi-elan.c index 52c27cab78c3..9b5b3b2281ca 100644 --- a/drivers/usb/misc/ftdi-elan.c +++ b/drivers/usb/misc/ftdi-elan.c @@ -665,7 +665,7 @@ static ssize_t ftdi_elan_read(struct file *file, char __user *buffer, { char data[30 *3 + 4]; char *d = data; - int m = (sizeof(data) - 1) / 3; + int m = (sizeof(data) - 1) / 3 - 1; int bytes_read = 0; int retry_on_empty = 10; int retry_on_timeout = 5; @@ -1684,7 +1684,7 @@ wait:if (ftdi->disconnected > 0) { int i = 0; char data[30 *3 + 4]; char *d = data; - int m = (sizeof(data) - 1) / 3; + int m = (sizeof(data) - 1) / 3 - 1; int l = 0; struct u132_target *target = &ftdi->target[ed]; struct u132_command *command = &ftdi->command[ @@ -1876,7 +1876,7 @@ more:{ if (packet_bytes > 2) { char diag[30 *3 + 4]; char *d = diag; - int m = (sizeof(diag) - 1) / 3; + int m = (sizeof(diag) - 1) / 3 - 1; char *b = ftdi->bulk_in_buffer; int bytes_read = 0; diag[0] = 0; @@ -2053,7 +2053,7 @@ static int ftdi_elan_synchronize(struct usb_ftdi *ftdi) if (packet_bytes > 2) { char diag[30 *3 + 4]; char *d = diag; - int m = (sizeof(diag) - 1) / 3; + int m = (sizeof(diag) - 1) / 3 - 1; char *b = ftdi->bulk_in_buffer; int bytes_read = 0; unsigned char c = 0; @@ -2155,7 +2155,7 @@ more:{ if (packet_bytes > 2) { char diag[30 *3 + 4]; char *d = diag; - int m = (sizeof(diag) - 1) / 3; + int m = (sizeof(diag) - 1) / 3 - 1; char *b = ftdi->bulk_in_buffer; int bytes_read = 0; diag[0] = 0; |