sg_start_req(): make sure that there's not too many elements in iovec
commit 451a2886b6bf90e2fb378f7c46c655450fb96e81 upstream. unfortunately, allowing an arbitrary 16bit value means a possibility of overflow in the calculation of total number of pages in bio_map_user_iov() - we rely on there being no more than PAGE_SIZE members of sum in the first loop there. If that sum wraps around, we end up allocating too small array of pointers to pages and it's easy to overflow it in the second loop. X-Coverup: TINC (and there's no lumber cartel either) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [bwh: s/MAX_UIOVEC/UIO_MAXIOV/. This was fixed upstream by commit fdc81f45e9f5 ("sg_start_req(): use import_iovec()"), but we don't have that function.] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1694,6 +1694,9 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
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md->from_user = 0;
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}
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if (unlikely(iov_count > UIO_MAXIOV))
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return -EINVAL;
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if (iov_count) {
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int len, size = sizeof(struct sg_iovec) * iov_count;
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struct iovec *iov;
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