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[PATCH] Fix buffer overflow in Omnikey CardMan 4040 driver (CVE-2007-0005)

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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>
This commit is contained in:
Marcel Holtmann 2007-03-06 22:12:00 +01:00 committed by Linus Torvalds
parent 266d4f4037
commit 059819a41d
1 changed files with 2 additions and 1 deletions
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3
drivers/char/pcmcia/cm4040_cs.c
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@ -273,6 +273,7 @@ static ssize_t cm4040_read(struct file *filp, char __user *buf,
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 @@ static ssize_t cm4040_write(struct file *filp, const char __user *buf,
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;
}