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[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>
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@ -273,6 +273,7 @@ static ssize_t cm4040_read(struct file *filp, char __user *buf,
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DEBUGP(6, dev, "BytesToRead=%lu\n", bytes_to_read);
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min_bytes_to_read = min(count, bytes_to_read + 5);
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min_bytes_to_read = min_t(size_t, min_bytes_to_read, READ_WRITE_BUFFER_SIZE);
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DEBUGP(6, dev, "Min=%lu\n", min_bytes_to_read);
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@ -340,7 +341,7 @@ static ssize_t cm4040_write(struct file *filp, const char __user *buf,
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return 0;
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}
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if (count < 5) {
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if ((count < 5) || (count > READ_WRITE_BUFFER_SIZE)) {
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DEBUGP(2, dev, "<- cm4040_write buffersize=%Zd < 5\n", count);
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return -EIO;
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}
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