[PATCH] Fix buffer overflow in Omnikey CardMan 4040 driver (CVE-2007-0005)
Based on a patch from Don Howard <dhoward@redhat.com>
When calling write() with a buffer larger than 512 bytes, the
driver's write buffer overflows, allowing to overwrite the EIP and
execute arbitrary code with kernel privileges.
In read(), there exists a similar problem, but coming from the device.
A malicous or buggy device sending more than 512 bytes can overflow
of the driver's read buffer, with the same effects as above.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/pcmcia/cm4040_cs.c b/drivers/char/pcmcia/cm4040_cs.c
index 0e82968..f2e4ec4 100644
--- a/drivers/char/pcmcia/cm4040_cs.c
+++ b/drivers/char/pcmcia/cm4040_cs.c
@@ -273,6 +273,7 @@
DEBUGP(6, dev, "BytesToRead=%lu\n", bytes_to_read);
min_bytes_to_read = min(count, bytes_to_read + 5);
+ min_bytes_to_read = min_t(size_t, min_bytes_to_read, READ_WRITE_BUFFER_SIZE);
DEBUGP(6, dev, "Min=%lu\n", min_bytes_to_read);
@@ -340,7 +341,7 @@
return 0;
}
- if (count < 5) {
+ if ((count < 5) || (count > READ_WRITE_BUFFER_SIZE)) {
DEBUGP(2, dev, "<- cm4040_write buffersize=%Zd < 5\n", count);
return -EIO;
}