firewire: nosy: ensure user_length is taken into account when fetching packet contents
commit 38762a0763c10c24a4915feee722d7aa6e73eb98 upstream. Ensure that packet_buffer_get respects the user_length provided. If the length of the head packet exceeds the user_length, packet_buffer_get will now return 0 to signify to the user that no data were read and a larger buffer size is required. Helps prevent user space overflows. Signed-off-by: Thanassis Avgerinos <thanassis.avgerinos@gmail.com> Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -148,10 +148,12 @@ packet_buffer_get(struct client *client, char __user *data, size_t user_length)
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if (atomic_read(&buffer->size) == 0)
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return -ENODEV;
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/* FIXME: Check length <= user_length. */
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length = buffer->head->length;
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if (length > user_length)
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return 0;
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end = buffer->data + buffer->capacity;
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length = buffer->head->length;
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if (&buffer->head->data[length] < end) {
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if (copy_to_user(data, buffer->head->data, length))
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